Most states are purple

About a year and a half ago (August 2005), having had discussions with many people about the supposedly new polarization of America’s population into red and blue states, and looking for a better visualization of the actual results, I was pleased to find the following website. The authors at Univ. of Mich. carefully describe some more accurate ways of portraying the proportions of votes in the last presidential election, where — like in most elections — the majorities were as often slim as they were wide. For the explanation behind the attached purple proportional cartogram, please see http://www-personal.umich.edu/~mejn/election/.

This sequence shows a progression from winner-takes-all state votes in 2004, to county votes, to shading by proportion of votes, to scaling the counties by the number of votes in them.

Having recently returned to my home state — long known for its extreme conservatism — after an absence of almost eight years, I was surprised at the broad mix of colors there, and particularly by the fact that my county was NOT the reddest county on the map…. though it was still quite non-blue. On the other hand, some places are just plain predictable — e.g. Provo and S.F./Berkeley.

At the time, I asked the authors about extending the study to several previous elections, and then devising a visually informative method of displayingtrends and changes over time (or we could make an animated GIF, I suppose). But I received no response. I guess it takes a lot of grad students to enter all that data… ;o}

Interstate highway system map, revised

I found an excellent diagram of the U.S. Interstate highway system on strangemaps’ blog. Although the post doesn’t say who originated the diagram, the discussion is excellent. [Update: strangemaps' previous post has a comment noting the map's source (http://www.chrisyates.net/store/fullinterstatemap-web.jpg), and indeed the image itself is signed Chris Yates 2007.]

However, there are numerous technical errors and omissions on the diagram. It appears the original artist intended to include all of the one- and two-digit interstate highways (as evidence, I see that he included the single-state I-4 and I-16 in Florida and Georgia, respectively), and that he intended to label cities at intersections of interstates. Along those lines, the deficiencies are listed below.

Route errors:
• The intersections of I-90, I-94, and I-25 (originally labeled Butte, Billings, and Buffalo) are all scrambled.
• The intersections of I-8, I-10, I-17, and I-19 (originally labeled Phoenix) are all scrambled.
• I-20 intersects I-10 almost 200 miles east of El Paso.
• Columbia is indeed at the intersection of I-20 and I-77, but nowhere near I-95 as shown.
• I-93 does not intersect I-91 at White River Jct, but rather much farther north.
• I-87 and I-89 do not exit the country together.
• Erie is indeed at the northern end of I-79, but that is at the intersection with I-90, not I-80.
• Almost all the routes in Pennsylvania are messed up (currently labeled Pittsburgh and Harrisburg).
• All of Wisconsin is missing.
• Many interstates in Illinois are missing, as well as others scattered around the nation.
• I-65 does not continue north past Chicago/Gary to Grand Rapids, and in fact the west end of I-96 is Muskegon, not Grand Rapids.
• I-75 does not end at Ft. Myers, but rather extends to intersect with I-95 at Ft. Lauderdale.

Other erroneous cities:
• Wilkes-Barre is not at the I-80/I-81 intersection.
• Raleigh is not at the I-95/I-40 intersection.
• Winston-Salem is not at the I-77/I-40 intersection.
• The intersection of I-20 and I-95 is at Florence.
• The intersection of I-70/I-15 is not at a city, town, or village named Monroe.
• Las Vegas isn’t at an intersection, so it shouldn’t be shown.

Missing routes:
• Part of I-94 is missing. It continues east of Minneapolis/St. Paul, to join with I-90 for awhile, then splits again at Madison WI, where I-94 heads east to Milwaukee WI and then south to the Chicago IL metropolitan area.
• Part of I-84 from Newburgh NY to its terminus in Massachusetts at I-90 is missing.
• I-64 east of I-95 to the Norfolk area is missing.
• I-40 east of I-95 to Wilmington is missing.
• I-76 from Pittsburgh to Cleveland is missing.
• Entirely missing are everything in Wisconsin, much of Illinois, and various regional and single-state highways: I-H1,H2,H3^*, I-12^*, I-24, I-26, I-27, I-37, I-39, I-43, I-49, I-59, I-72^*, I-74, I-82, I-97, and I-99.

So I have modified the map greatly, as shown below. I have extended each highway to its actual end, or where it extends into Mexico or Canada, including the last major city, if any. Still missing are I-12 (a bypass around Lake Pontchartrain, north of New Orleans — in fact this was the original route of I-10, and the piece connecting down to N.O. was called 55 and 59), and I-72 in Illinois, for which there just isn’t room, and the Hawaiian highways I-H1,H2,H3.

[updated 19 March 2007] Moved I-64 south, between Staunton and Charleston; replaced El Paso with Las Cruces; replaced Portland (ME) with Houlton; labeled the blank dots at Green Bay and Blacktown (PA); merged Ft. Lauderdale into Miami; extended I-69 and I-94 to Port Huron; added more intersection names along I-10, I-39, I-57, I-69, I-70, I-77, I-80, I-81, I-82, I-90, I-93, I-95, I-99; completely revamped the WI-IL-IN-MI area to separate Chicago and Gary and clean up (slightly) the IL bramblebush, and adding I-72 and I-88; added I-12.