DIY Animation with Census Explorer

Recently, I attended the ESRI Federal GIS conference here in Washington DC. I was canvassing the vendor exhibits looking for free pens, and maybe, if I was lucky, notebooks, when I came across the U.S. Census Bureau display. The nice people there showed me a very cool tool for viewing basic U.S. demographic data over time and at a variety of spatial scales. It’s called Census Explorer.

I have used Census data before to do some analysis (and write a post) on age and income in U.S. counties, but I had to download the data and map it myself. But Census Explorer is an online map interface. You can zoom from State to census tract level, and toggle between data from 1990, 2000, and 2012.

I zoomed in on the Milwaukee, WI metro area and looked at the percent of population age 65 and over at the census tract level. Toggling from 1990 to 2012, I could make out a clear pattern – the suburbs were becoming older at the expense of the central city – but I had no way to export this as a single image. So I went low tech. I took screenshots of each image, aligned then, and made a GIF using a free online service.

age animation

It’s not perfect, but the demographic change over time is clearly visible. Actually, I was surprised to see such a clear pattern in Milwaukee over the last 22 years. Any idea why this is happening?

Where Do The Elderly Live?

If your own mother does not read your blog, you know it’s time to pack it in. Fortunately, my dear mom is a faithful reader. She works in the geriatric care management industry – basically coordinating medical care for elderly patients – and asked me if I could put together some visualizations of old age in America. I thought it would be a good idea to start with figuring out where exactly older Americans live. This turned out to be a good chance to play with CartoDB and US Census Data. See the end of the post for more details on how I put these maps together, and click on the map images to access the zoomable, clickable CartoDB versions. So here you go mom, this one’s for you.

percent over 65

Percent of Population Over Age 65

About 14 percent of Americans are over age 65. But, as you can see from the map above, they are not evenly distributed across the county. At the county level the percent of residents over 65 varies from 10 percent to almost 50 percent. You can see that the Great Plains, parts of the west,  northern Michigan and Wisconsin, and  Florida all have concentrations of these older counties.

pop over 65 per sqr mile

People over age 65 per square mile

But if we are interested in where the most elderly people live, the percentage of population over 65 is really not the most instructive. After all, many of the counties with high proportions of elderly people are rural counties with low population densities. A more instructive metric would be the number of people over 65 per county per square mile, or the population density of elderly. We can get this by multiplying, in each county, the percent of people over 65 by the total population density. That’s what the map above shows. It looks a lot different than the map of elderly population by percent. You can see that even though areas like the northeast corridor (Washington DC – Boston) do not have an especially large share of elderly residents, the elderly population density is high simply because the total population density is high.  Perhaps the most obvious conclusion we can draw from this map is that there are an awful lot of elderly people in the state of Florida.

old dense poor

Counties with over 25 people over age 65 per square mile and median household income over $50,000

Finally, as an illustration of the sort of things you can do with CartoDB, I made a map (above) that shows counties with relatively high densities of elderly residents and below average median household incomes (click on the image and zoom in to see the smaller urban counties). This might be useful if you were interested in areas where social services for the elderly might be best directed.

Technical Notes: Finally, just a word or two about how I made these maps. First, I downloaded data from the U.S. Census QuickFacts service. With these data you can produce an Excel spreadsheet with county-level attributes on demographics, race, poverty and incomes, and business. I generated another column of population density of residents over 65. Next, I downloaded a shapefile of U.S. counties with state and county FIPS codes. I uploaded both of these into CartoDB and joined the tables by matching the numeric FIPS codes. Finally, I used CartoDBs widgets and filters to produce the chloropleth maps above. To see the maps in CartoDB, click on the images. Click on individual counties to see selected demographic and economic attributes for that county.