Table of Contents
By: Rowyn Lea
Anyone who has been to Rome in last few hundred years would notice one major thing about the roads: They are paved with black cobblestones. These cobblestones are a part of Rome’s charm and elegance. They give the city a unique feel unlike any other.
Cobblestones as a road surface in Rome can be dated back to the 1700s. In the mid-1700s, Pope Clement VIII Corsini started having the streets of Rome be paved with cobblestones, or as they are known locally, “sampietrini” which means “little stones of St. Peters” (Rome, 2014). There are stories about how Pope Sixtus V had the first Roman cobbles laid in Piazza San Pietro, in Vatican City, because of the poor condition of the old paving stones (Rome, 2014). This was before the 1700s. The stones have only been used in Rome for a few hundred years which makes them relatively modern when compared to the ancient ruins surrounding the roads. The sampietrini are roughly pyramid shaped volcanic rock that is cut by hand to be the correct shape to fit and then hammered into a sand base (Rome, 2014). The volcanic rock was originally from quarries located all around Rome, but the last quarry was closed over a decade ago (Fisher, 2005).
The cobbles were put in place to redo the road surface that was in use before them. The older road surface was most likely made from larger paving stones, much like on the via Appia (Figure 1), that were used in Rome’s historic center before the cobbles (Fisher, 2005). The via Appia was one of the first Roman roads built with large paving stones that led to Rome.
|Figure 1. Via Appia in summer 2017 (photo by author).|
In the last decade, there has been an increasing amount of asphalt paving in, around, over, and in place of the traditional sampietrini. The balance between cobblestones and asphalt is the modern Roman road problem that is plaguing the city currently.
This article is going to look in-depth at a few different aspects of the roads in Rome. First, I will discuss the materials that are used in Rome, how they interact, and the maintenance that is associated with the material. Besides the material used for the road itself, it is also interesting to look at how the types of roads and the multimodal methods of transportation interact with each other in the heart of the city. That will lead into some of the current issues that have developed by having so much motorized vehicle traffic around such a major tourist destination. I will complete this review of the modern roads in Rome by mentioning some of the local discussions that happened when the asphalt first started becoming popular in Rome and what is next for Rome in the coming years.
Building new roads in and around Rome is a difficult thing to do, I would say near impossible. First, there are problems with the limited space. The inner city of Rome, with the ancient ruins and the Vatican, is incredibly densely packed with buildings and historic roads and piazzas. The streets of this part of Rome must be built around ancient buildings and ruins that are hundreds to thousands of years old. The roads that run through this part of the city have been in place for hundreds of years. Figure 2 and 3 show a comparison of what Rome looked like in the 1600s and what it looks like today. The streets follow roughly to what they did back then. Also, building brand new roads means excavating and digging in new areas. This is very difficult in Rome because there are so many ancient artifacts buried under the soil. According to Adriano Morabito, it costs huge amounts of money and time to invest in the archaeologists and tools necessary to make sure precious artifacts are not ruined by the construction of new roads. Usually this is a cost burden that public agencies are unwilling to take on. Instead of building new roads, existing roads are maintained by resurfacing them.
|Figure 2. Map of Rome at the end of the 1600s (Battlemaps, n.d.).|
|Figure 3. Map of Rome in 2017 (Google, n.d.).|
The roads in Rome are paved with two different materials. Most of the main vehicle roads in Rome are now paved with asphalt or are transitioning towards being paved with asphalt. This means that vehicles can drive at higher speeds because the asphalt roads have a smoother road surface to drive on compared to the sampietrini that was used before. It also reduces road noise from the tires. When tires drive over cobblestones, the gaps between the stones cause a louder noise than when the tire is in continual contact with the road surface. The smaller side roads along with most piazzas are typically covered with cobblestones. Although most of the sampietrini can be reused around the city, sometimes new cobbles need to be brought in when old ones get destroyed. The local quarries that supplied all the volcanic rock have closed, so when new stones do need to be brought in they are imported from other countries. There are different locations that these imported cobbles come from, depending on who is asked, but the consensus is that the stones come from Asia (Johnston, 2013). These stones, according to Roberto Giacobbi are “sufficient” but not as good as using the local sampietrini (Johnston, 2013). At first glance when walking around Rome it is difficult to distinguish the difference between the local and imported stone. The only noticeable feature is the slight difference in color (Fisher, 2005). That is why the cobbles are reused, to keep as much of the local rock in Rome as possible. When the major roads started being converted from sampietrini to asphalt, the areas where the cobbles were removed produced a sufficient number of cobbles that could be saved for later reuse on the smaller roads around the city.
Although cobblestones are a rough surface to bike or drive motorized vehicles on, when installed correctly, it can last a long time. Roberto Giacobbi, who has been laying sampietrini for about 30 years, stated that though cobblestones take longer to put in correctly, they will outlast the asphalt roads by 10 times (Fisher, 2005).
Travertine is a local stone that is found all around Rome and was used by the ancient Romans for numerous big projects including the Colosseum and triumphal arches. It is still used to this day, there are numerous active quarries located only a short drive from the center of Rome. Figure 4 is a family owned quarry that I was able to see and experience first-hand. In roads, travertine can be seen as curb stones that define the edges of sidewalks and car barriers (figure 5). It is astonishing that the same type of rock is still the material of choice that is used to build new projects for over 2,000 years.
|Figure 4. Active travertine quarry near Rome (photo by author).|
|Figure 5. Travertine curb installed at a new sidewalk location (photo by author).|
Mixing of Sampietrini and Asphalt
There are places in the city that have a mix of asphalt and cobblestones. I see this as defeating the benefits of both types of materials. I saw this mismatch of material in a few different ways when walking around Rome.
First, on a cobblestone street there are seemingly random patches of asphalt scattered around. From what I gathered, the patches appear after there is underground maintenance, when crews take out the cobbles and dig out the sand to tend to the pipes that are buried beneath the road surface. Instead of relaying a smooth sand base and returning the removed cobblestones, they will instead mix up a batch of asphalt and lay that down, often creating uneven edges where the asphalt meets the edges of the cobbles (Figure 6 and 7). I walked past such a patch over the course of a few weeks. This might be a singular instance, but over time the asphalt began to sink around the cobblestones. By the end of my time in Rome, it almost looked like a sinkhole or pothole. This could have happened if the crew did not do a good job of compacting the base beneath the asphalt so that after the ground settled from vehicles and rain, voids started to open up under the asphalt thus creating the appearance of a sink hole.
|Figure 6. Small patch of asphalt between cobbles (photo by author).|
|Figure 7. Asphalt section in cobblestone area (photo by author).|
There are also numerous areas around Rome where cobblestones are simply paved over with asphalt (Figure 8). In theory, I think this could be a smart idea. The cobblestones, if they were laid correctly, would act as a good, sturdy foundation for the asphalt to go on. The sand layer with the cobbles can act like a gravel bed for the asphalt. Using the cobbles in this manner would be cost efficient by not tearing them out. The contractor does not have to bring in a gravel truck to lay a base for the asphalt. There are some down sides to method. If the cobblestones were not well placed or have come loose over time, which is quite common when looking around piazzas and streets, it could lead to a short lifespan of the asphalt road. By paving over the limited supply of sampietrini, it means there are less available local cobbles left for maintenance of the remaining cobblestone streets.
|Figure 8. Asphalt covering cobblestones (photo by author).|
Another combination that I have seen is where cobblestones are the paving surface but instead of using sand as the base with gaps around the stones, the gaps are filled with asphalt (this can be seen on the edges of Figure 7). The benefit that this might have would be that cobbles will stay tightly packed together for longer periods of time compared to if it was just sand. Although, if the sampietrini does come loose, it will be more time consuming and expensive to fix the road. This method is a way of making the cobblestone road surface permanent. Unfortunately, one of the best part about the sampietrini that are used in Rome is that they can be moved if need be.
In some areas of Rome, there are areas of cobblestones where the surface has been painted for safety reasons. A problem I noticed with painted cobblestones is that the paint can become quite faded due to vehicle tires continually running over such a smooth volcanic rock. This can be an ineffective and inefficient way of creating safe guides for people to follow. The sampietrini that are painted need continual maintenance as it is a never-ending task to create the crosswalk and sidewalk marks. I passed numerous areas where the paint was almost completed worn off the tops of the cobbles, but this did not seem like a big deal to the local people. One such area is shown in Figure 9. These areas were usually located on side streets and small piazzas where there were typically pedestrians milling around and walking in and around the parked cars. Painted lines on asphalt roads, such as Figure 10, appeared to last longer than paint on cobbles.
|Figure 9. Most of a white crosswalk has been worn away (photo by author).|
|Figure 10. Crisp, new crosswalk painted after a repaving job (photo by author).|
Some areas have white rock cobblestones. A benefit of using white cobblestone instead of paint for the white crosswalk marks is that the crosswalk can be made as a permanent part of the road (Figure 11). By using white cobblestones instead of the traditional sampietrini, the white stripes of the crosswalk stay obvious for as long as the cobbles stay in the road. This means that the maintenance for maintaining the crosswalk will be minimal, thus saving time and money for the local government. The only downside to using this method is that it creates a permanent crosswalk, so if there are plans to change the location of the crossing, the cobbles will need to be removed as opposed to just having the paint wear off of the rocks.
|Figure 11. White cobblestones to make an ever-lasting crosswalk (photo by author).|
Working Under Roads
When crews need to work under a cobblestone road surface of sampietrini, to get to the correct location, all they need to do is pull out the cobblestones and dig out the underlying sand and dirt, which can be done with hand tools and small digging equipment (Figure 12 and 13). In contrast, an asphalt road requires larger equipment to excavate the location because asphalt needs to be broken into pieces to be hauled away. The sampietrini can be saved and then reused when the crew is done working under the road. If the surface is asphalt, the crew needs to bring in a load of asphalt and a roller, depending on the size, to compact the asphalt (Figure 14).
|Figure 12. Workmen working in a small area beneath a cobblestone street (photo by author).|
|Figure 13. Removed sampietrini and dirt to access utilities underground (photo by author).|
The downside of needing to work under cobblestone roads is that the cobbles need to mainly be removed by hand, or at least they need to initially be removed by hand. It is more manual labor to remove the sampietrini than it is to remove asphalt. When putting the asphalt or sampietrini back, at the end of the project, it still requires more manual labor for the cobbles than the asphalt. There are machines and equipment that can help crews pave and compact asphalt but there are only 8 skilled people in Rome who know how to properly hammer in sampietrini in by hand (Lewis, 2005).
|Figure 14. Paving crew using a roller to compact the asphalt (photo by author).|
Potholes and small sinkholes can be seen all around Rome and can open at any time. It is difficult and expensive to go around Rome continually fixing small holes that open in asphalt due to all the heavy machinery required. I saw a relatively large pothole, Figure 15, but because it is along the side of the road it will probably be years before it gets repaired. When I talked with Adriano Morabito, he mentioned that sinkholes are a common occurrence in Rome. Underneath the current Rome is an older version from the past. New roads go right over the top of ancient houses and shops. When continual traffic or heavy traffic in a new area drives over these underground voids, they become visible. This is a problem that will be present in Rome for the foreseeable future as it is impossible to know what is underneath the version of Rome that stands today. Sometimes these sinkholes can be small and sometimes they can be huge, a tiny one I saw is shown in Figure 16.
|Figure 15. Asphalt pothole along the edge of a street (photo by author).|
|Figure 16. What appears to be the beginning of a sinkhole underneath asphalt paving (photo by author).|
Sinkholes in Rome
Sinkholes in Rome, and Italy in general, are not an uncommon occurrence. Sinkholes can be classified into two main categories, natural and anthropogenic (Parise, 2013). The natural sinkholes can happen for different reasons but usually are the result of water soluble rock that creates voids under ground that will eventually collapse. It can roughly be determined where these natural sinkholes will happen just by mapping the locations of the water-soluble rock. It is the anthropogenic sinkholes that can be more difficult. The precise locations of underground caves, building, and mines are not well known. In Rome, there are underground buildings that are even on top of underground mines. I visited such a place, Basilica Santi Giovanni e Paolo, which has an old Tuff mine underneath it. This creates challenged when building as there needs to be a strong foundation that goes beneath the excavated layer so that the buildings do not collapse.
In order to better understand where these caverns are, new technology is being used to find and map these locations. Along with traditional mapping, there is also systematic surface and subsurface investigations, direct and indirect surveying, and analyses obtained from bored holes (Pepe, 2013). These techniques are allowing for detailed maps to be created that show the location and size of these potential sinkhole sites.
Types of Roads and Modes of Transportation in Rome
In Rome, there are numerous ways to get around the city. Vehicle roads, which carry busses, cars, small delivery trucks, motorcycles, and mopeds, are certainly the most prevalent and reach virtually every part of the city. The biggest roads cutting through and around the heart of Rome are all paved with asphalt. Some of these major thoroughfares through Rome include Lungotevere dei Vallati, Lungotevere Raffaello Sanzio, and Corso Vittorio Emanuele II. The smaller roads are almost all cobblestone and are shared by pedestrians and vehicles. The bigger roads have sidewalks that are either raised on the edges or are separated from the traffic with metal poles or white lines. The sidewalks are not always protected for pedestrians because motorcycles, mopeds, and occasionally cars will park on the sidewalks (Figure 17). This makes it dangerous for people to walk so close to the quick moving vehicles.
|Figure 17. Car parked on a small sidewalk forces people to walk down the middle of the street (photo by author).|
As much of the city is paved in uneven cobblestones, bicycling is not a very common mode of transportation. It is difficult to ride a bike over cobblestone and challenging to ride on the asphalt roads while competing for space with the faster vehicle traffic. There are a few designated bike paths in the city, but they are hardly ever used because they do not go anywhere in particular and stop and start in a seemingly random way.There is a bike path along the Tiber River, it is somewhat used by cyclists and runners, but the river has been walled off and plays little part in Rome’s culture. Although Rome is a walkable city, where most things are all relatively close together, vehicle traffic can be immense. In the heart of the historical center, the Piazza Venezia, a big piazza alongside the monument of Victor Emmanuel II, vehicles are zooming around the piazza even though this is a major pedestrian area.
In the inner city of Rome, vehicle traffic is limited to only people who have a permit for their vehicles and is enforced with cameras and license plate readers that send fines to anyone who violates the rules. You can read more about that system by going to Traffic Management in Rome.This means that in certain parts of the city there should be less traffic and vehicles driving around. There still seems to be too many vehicles present and not enough room for all of them. The historical city center, where most of the tourists’ sites are, should be pedestrian friendly but is not because there are major vehicle roads that run straight through that area.
Issues Caused by Vehicles
In Rome, most designated pedestrian areas have vehicles driving around unless drastic measures are taken. There are pedestrian signs, such as in Figure 18, that can be seen around the city showing where pedestrian areas are, but they do little to prevent cars and mopeds from driving anywhere they can fit. When talking to Adriano Morabito, he said that ideally, pedestrian areas should be where people do not need to worry about looking out for cars driving by and mopeds speeding through, but that is not what usually happens. After observation I have found very few places in Rome that people do not need to be constantly on guard for fear of being hit by a motorized vehicle. This is one area that Rome struggles with, making sure that all traffic, from foot to tour bus, is safe when traveling in Rome.
|Figure 18. A pedestrian zoning sign at an intersection (photo by author).|
To help fix the problem, pedestrian bridges use chains and specially designed metal structures to allow bicycles and wheelchairs through but keep cars and mopeds off. This design seems like a great idea, there are bridges over the Tiber River that only pedestrians can walk on. But the barriers are limiting for people. They can be difficult to walk through because they have sharp turns. A person in a wheelchair or even someone pulling a cart may find it difficult to get through the barriers onto the bridge.
Physical barriers which create curbs in the middle of a road are also built to keep cars out of piazzas (Figure 19). These are usually made with Travertine stones and sampietrini with a gap in the middle to allow wheelchairs and bicycles through. Mopeds also will use this gap to drive through to where they ultimately want to go. These barriers do help some but not enough.
|Figure 19. Physical barriers to keep vehicles from going down the street (photo by author).|
In theory, there is a good balance to combining bikes, people, and vehicles safely so that everyone can get around the city. I spoke with Tom Rankin and he said that every year people get hit by cars and mopeds while crossing the roads in Rome. Rome and Seattle have similar pedestrian fatality statistics per 100,000 population. In 2015, there were 39 pedestrian deaths in Rome and the population of the city was 2.87 million (Rome on Edge, 2015). In 2014, Seattle had 7 pedestrian fatalities (Fatal, 2014). Though 7 is less than 39, the population for the city of Seattle was about 650,000 (United, 2016). Comparing these, in Seattle there was 1.1 fatalities per 100,000 population and 1.4 fatalities per 100,000 population in Rome.
To help separate people and cars, barriers are one of the most effective ways to this and that is why they are used today in the city. Most small roads have pedestrians milling about in the middle, as there typically are not any sidewalks, or very small sidewalks, for people to walk on. This helps keep the speed of vehicles lower when they drive through as they must slow down to avoid people, but this is dangerous for everyone. Sometimes people and cars are only separated by a few inches. This is a challenge that even the best engineers have a difficult time resolving.
Rome’s Road Future
In 2005, Rome’s mayor Walter Veltroni, supported the push for more of Roman roads to be paved with asphalt instead of sampietrini (Lewis, 2005). The local government gave reasons why the switch from cobbles to asphalt for more of the major roads through the city. Veltroni cited the increasing costs of using cobbles, which he said costs about twice as much as asphalt, as the reason for wanting to switch (Fisher, 2005). Safety concerns, noise reduction, and monument stability were the reasons for asphalt over cobblestones that chief of Rome’s public works department, Giancarlo D’Alessandro, gave (Fisher, 2005). The sampietrini can be dangerous when it rains for pedestrians and two-wheeled vehicles, as they become slick when wet. D’Alessandro wanted to assure everyone in 2005 that the switch to asphalt would not greatly change the appearance of Rome to everyone, since the government only wants to convert the major vehicle traffic thoroughfares from cobblestone to asphalt through the city (Fisher, 2005). Pedestrian walkways and historic piazzas such as Piazza Venezia, shown in Figure 20, Piazza Novona, and Piazza della Rotonda, city officials have affirmed that they will stay covered with sampietrini (Fisher, 2005).
|Figure 20. Piazza Venezia, well maintained cobbles creates a nice driving surface (photo by aurthor).|
Though Romans might not prefer asphalt to cobblestones, they are not complaining about the change in road surface as much expected considering how much pride locals have about their sampietrini (Fisher, 2005). This could be because anyone who drives a scooter, car, or rides a bus knows how uncomfortable it is to drive on cobbles. When I was taking the bus around the historic center, riding over rough, bumpy patches of sampietrini roads it felt as if the bus was going to shake apart. The rattles and loud noises coming from the bus as it drove around the city would be a concerning sight to witness in the United States, but in Rome it is what people have become accustomed to. The sampietrini are also known to create dangerous potholes when they come loose or are missing (Barbra, 2005). These potholes pose threats to vehicular safety as well as pedestrian safety. Others are glad to see some of the cobbled streets turn to asphalt as in recent times, sampietrini have been used as weapons during street riots (Gagliardi, 2005).
An engineering professor at La Sapienza University, Carlo Giavarini knows that it is a challenge to balance the advantages of safety, aesthetics, and technical needs, especially since Rome has limited money (Fisher, 2005).
Some of the heavily trafficked pedestrian areas have been upgraded with a different type of material than that of sampietrini or asphalt. They are instead being redone with larger paving stones that are flat and are laid over a concrete base (Rome, 2014). They are easier for people to walk on and quieter for vehicles to drive on compared to sampietrini but are more aesthetically pleasing than asphalt. In 2011, the Mayor of Rome, Gianni Alemanno, mentioned his plans for road renovations that were not asphalt like Veltroni was pushing for in 2005. Though I did not see any of these new paving stones used as a road surface, I did see them used as the paving surface on a few raised sidewalks along busier roads. Walking towards the Piazza di Spagna, the sidewalks lining the picturesque sampietrini uses these larger paving stones. Maybe in the years to come there will be more use of these stones as a new type of road surface in Rome.
Historic Rome and its ancient buildings and roads were built thousands of years ago. This long history of engineering and building has been maintained by many of the same methods and materials that were used by ancient Romans. Because of the long history of the city, Romans tend to change and upgrade very slowly over time when compared to other parts of the world. The sampietrini have been used as the main road surface in Rome for hundreds of years and are looking at new ways to maintain the roads in the city. Just in the last decade or so they have started to switch to asphalt. There are many reasons that Romans want to adapt new technology for their roads. It is interesting to look at how Rome makes progress and “modernizes” at its own pace but it is a city that has been in existence for thousands of years.
It may be difficult for Rome to move away from the treasure that are the sampietrini. They hold history, meaning, and pride for Rome. They will continue to be the main surface for ancient Roman areas and in locations that have little wear or use and have not had to be removed for other needs. Change is inevitable though, so it has started to happen in the primary vehicle transportation areas around the city. There are roads and areas of Rome that will still have the sampietrini for the foreseeable future and that brings comfort to those who value what the cobbles mean to the city.
The areas that have been converted to asphalt show the clash between the modern motorized vehicles and the ancient cobblestone roads. Cobbles create impractical problems for modern vehicles. I believe that the city did the best they could in 2005 to make changes that would benefit all of the stakeholders in the situation.
The traffic use of the road will still be a major issue independent of the material used for the surface of the road, curbs, and other road markings. This might be a bigger problem than just a road and road materials can fix. I do not think that cars will stop parking on the sidewalk and in other nonstandard areas just because the road was made of asphalt or road markings were made a certain way. There are other social and historic use factors at play that should be considered that are outside of the scope of this article.
A plan could be made to assign a road surface preference for each area based on the use of the road, pedestrian safety, and historic preservation needs. Regardless, this article can act as a stepping stone for research into a number of different directions that can, and should, be looked at in the future to see where Rome’s roads are headed to next.
Barbara McMahon in Rome. (2005, July 25). Road to ruin Rome to asphalt over its ‘dangerous and damaging’ cobblestones.(Guardian Foreign Pages). The Guardian (London, England), p. 15.
Battlemaps. (n.d.). Rome, 1690, Roma Novissima & Accuratissima, Falda, Feuille, City Plan. Retrieved December 08, 2017, from https://www.battlemaps.us/rome-1690-roma-novissima-accuratissima-falda-feuille-city-plan/
Fatal car crashes and road traffic accidents in Seattle, Washington. (2014). Retrieved December 09, 2017, from http://www.city-data.com/accidents/acc-Seattle-Washington.html
Fisher, I. (2005, September 01). For Its Motorists, Only Parts of Rome Prove to Be Eternal. New York Times (1923-Current File), p. A3.
Gagliardi, Giovanni. “Roma dice addio ai sampietrini asfalto anche nelle vie del centro.” La Republicca, 13 Jul. 2005, http://www.repubblica.it/2005/g/sezioni/cronaca/sampie/sampie/sampie.html
Google. (n.d.) Retrieved December 7, 2017, from https://email@example.com,12.492079,5094m/data=!3m1!1e3?hl=en&authuser=0
Johnston, A. (2013, May 24). The uneven charm of Rome’s cobblestones. Retrieved December 01, 2017, from http://www.bbc.com/news/magazine-22639754
Lewis, Aidan. (2005, July 31). Ancient cobblestone no match for Rome’s modern traffic loads; Labor-intensive, costly repairs force the city to restrict ‘sampietrini’ roads to pedestrian areas. The Houston Chronicle (Houston, TX), p. 25.
NBC News. (2005, July 25). Rome trading cobblestone streets for asphalt. Retrieved December 01, 2017, from http://www.nbcnews.com/id/8700967/ns/world_news-europe/t/rome-trading-cobblestone-streets-asphalt/#.WiHxQkqnGCo
Parise, M., & Vennari, C. (2013). A Chronological Catalogue of Sinkholes in Italy: The First Step Toward a Real Evaluation of the Sinkhole Hazard. Full Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst. doi:10.5038/9780979542275.1149
Pepe, P., Pentimone, N., Garziano, G., Martimucci, V., & Parise, M. (2013). Lessons Learned from Occurrence of Sinkholes Related to Man-Made Cavities in a Town of Southern Italy. Full Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst. doi:10.5038/9780979542275.1150
Rome, J. (2014, December 09). ‘Sampietrini’ – The streets of Rome. Retrieved December 01, 2017, from https://romeonrome.com/2013/01/sampietrini-the-streets-of-rome/
Rome on Edge of Breakdown. (2015, June 17). Retrieved December 09, 2017, from http://www.corriere.it/english/15_giugno_17/rome-on-edge-of-breakdown-3846540e-14ec-11e5-9e87-27d8c82ea4f6.shtml?refresh_ce-cp
United States Census Bureau. (2016). QuickFacts. Retrieved December 09, 2017, from https://www.census.gov/quickfacts/fact/table/seattlecitywashington/PST045216