An article at the Urbanophile gives us a helpful graphic explaining the old and new “Donut” conceptions of the city. In the “Old Donut,” we have an impoverished central city with a ring of thriving suburbs around it.
An example of that model appears in this graph, which shows the percentage of adults over 25 with college degrees in the Charlotte, NC metro area in 1990. The x-axis is distance from the center of downtown.
Local governments across the country have come under increasing fiscal strain in recent years, with several being forced to declare bankruptcy. The problems range from pension programs and decaying infrastructure to falling revenues from industrial and sales taxes as manufacturing gets offshored and shopping happens online. In Virginia, cities are further constrained by annexation laws that prevent them from expanding with their metropolitan area and gaining revenue from greenfield development or wealthier suburbs.
Recently, I’ve been comparing a number of traits of metropolitan areas based on distance from the core. Here I’m looking at the average densities of each metro area as you travel outwards from the center, calculated using census blocks and 2010 short-form census data. I’ve graphed them in groups of three. Cities with a strong core will have high densities on the left (near the center) that fall off as you travel outwards. Cities whose densities fall off quickly on the right have clearer edges, while those that taper off slowly are more spread out. Click on the graphs to view them full screen.
First are the three major metro areas. Note that the Northern VA graph includes only Virginia census blocks, not the rest of the DC area. Northern VA has the largest population by far, with fairly high densities even several miles into the suburbs. Richmond has the smoothest curve. I used downtown Norfolk as the core for Hampton Roads, but the area’s polycentricity is obvious.
As our regular readers already know, I’ve been playing around with a lot of dot density maps lately. Today, however, we are releasing something new I think you might enjoy even more.
We decided to rehash Brandon Martin-Anderson’s idea of plotting one dot for every person in the United States, but with an added twist. The new Racial Dot Map is an American snapshot; it provides an accessible visualization of geographic distribution, population density, and racial diversity of the American people in every neighborhood in the entire country. The map displays 308,745,538 dots, one for each person residing in the United States at the location they were counted during the 2010 Census. Each dot is color-coded by the individual’s race and ethnicity.
The map is fully interactive so you can zoom into any neighborhood you wish. You can read more about the map and how we created it here.
Among those of us who love old maps, the good people at the Atlas of Historical County Boundaries project have digitized and uploaded historical information on the shape of American counties. With this data one can animate how America’s political boundaries have changed since the founding of the Massachusetts Bay and Virginia Colonies. The above video shows historic county boundaries from 1630 to 1910 (shortly after Oklahoma and Indian Territory joined to form the State of Oklahoma in 1907). Please note these boundaries show the creation of government-defined geographic units, not necessarily where population is located.
Another great thing about this data is the level of detail available. For instance, focusing on the monumental changes that Virginia has gone through is quite interesting:
Note the emergence of many of Virginia’s Independent Cities at the turn of the 20th Century.
Things get more interesting when these county files are merged with historical census data. Inspired by our previous post on “Every person gets a dot,” I decided to look at county population dot densities from the first United States Census of 1790 to the recent 2010 Census. Here, every dot represents 5,000 people:
Artist Neil Freeman published a map of the United States redrawn to have 50 states with equal population, an art project that addresses what he says is “the fundamental problem of the electoral college”: “that the states of the United States are too disparate in size and influence.”
In today’s post I’ll talk about Chapter 3, which covers population density in the U.S. Population density tells us about the concentration of people in residential areas. From this measure we get an idea of how closely people live to each other. In this country, population density varies from more than 100,000 people per square mile in places like New York to just over zero people per square mile in places like remote Alaska.