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.
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.
No it’s not a party line. It’s an almost perfectly straight line running north-south along 16th Street, passing through the White House, and then continuing along the Potomac River to the south. It divides two very different sides of the DC area.
These graphs are a cross-section of the DC area that looks at how the city changes as you travel from the center to the periphery. I’ve split the graphs into two sides based on the east-west dividing line. You’ll notice the first one or two miles to the east are much like their western counterparts (this is essentially the area around Capitol Hill and the National Mall). After that, the two sides diverge pretty dramatically.Continue reading →
With input from Hamilton, I’ve been looking recently at how metropolitan areas change as one travels from the center to the periphery. The following charts show the percent of the population 25 and older with bachelor’s degrees. The graphs are based on concentric rings coming out from the center of downtown. I’ve included reference maps with distances and put lines on the graphs to correspond to the circles on the map.
It’s important to note that this is for adults who are 25 and older. While college towns have high numbers of educated residents and that shows up on the graphs, these numbers do not include actual undergraduate students or recent graduates.
Data for 1990 and 2000 comes from the long-form census. Data for 2012 is from the American Community Survey’s 2008-2012 5-year estimates. The census long form survey disappeared after the 2000 census, so questions that would have been on the long form (like education level) are now collected as part of the American Community Survey.
Metropolitan Statistical Areas (MSAs) or Metro Areas are perhaps the most common way to define an urban region. Because many urban areas cross into multiple localities, such as in Hampton Roads, MSAs are frequently used in the public and private sector to understand an urban area and its suburbs. Despite the widespread usage of MSAs, it is actually very difficult to find an up-to-date map of Virginia’s MSAs, which is why I created this updated map following the 2013 definitions from the Office of Management and Budget.
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.