Capitals Aligned

A query landed on the Twelve Mile Circle from a search engine as they often do. Our anonymous visitor was curious about "capital cities interstate." It took me a little while to figure out what he really wanted to know. I believe he was curious to discover the small number of U.S. state capital cities that are not served by Interstate Highways, a topic covered previously. That’s my guess and that’s where the search engine pointed him so hopefully all went well.

That got me thinking about the query differently. What if I took it literally? Let’s imagine a scenario where someone wished to visit state capitals on a long-distance trip. I don’t know, maybe our traveler wanted to create a photo collection of state capitol buildings or something — don’t be judgmental, people do that! — and for some reason he wanted to remain on a single Interstate Highway the whole time between points. Which Interstate Highway connects the most state capitals?

I didn’t conduct an exhaustive examination so I can’t guarantee that these are the absolute best results. I think they’re pretty good though.

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Interstate 80 seems to be the most optimal example to me. Five state capitals can be found along its length: Des Moines, IA; Lincoln, NE; Cheyenne, WY; Salt Lake City, UT; and Sacramento, CA. This can be accomplished with 27 hours of driving over 1,724 miles (2,774 kilometres). I’ll add a little caveat at this point. The highways I examined may not always plow directly through each city. Sometimes they provided a bypass in close proximity while skirting the city center. Thus, whether a highway actually serves a city depends upon one’s tolerance to proximity. The Interstate 80 example seemed to be the cleanest one with minimal bypassing based upon my quick eyeballing.

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I found another example in the crowded northeast corridor along Interstate 95. I wasn’t too surprised. States tend to be smaller with capitals located near the Atlantic coast, an artifact of colonial times when ships were a primary means of transportation. Five state capitals aligned again: Augusta, ME; Boston, MA; Providence, RI; Trenton, NJ; and Richmond, VA. Boston might be the ringer here. I-95 bypasses the city core by several miles (map). I can sense an opportunity for someone to claim that I-95 doesn’t really run through Boston. Perhaps one could also add the national capital, Washington, DC to this list. I know, it’s a slippery slope. All of these capitals could be claimed during a 747 mile (1,200 km) trek. Under the absolutely best conditions it would require 14 hours of pure driving hell. This is not a journey for the timid.

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I’m going to call Interstate 35 a four-plus example. There are definitely four state capitals: St. Paul, MN; Des Moines, IA; Oklahoma City, OK; and Austin, TX. The "plus" pertains to Topeka, KS. Topeka isn’t located on I-35, however, it’s found on a spur of that highway with the designation I-335. I might let that one slide except that it’s a fifty mile (80 km.) spur. It doesn’t have sufficient proximity, in my opinion, for me to count Topeka as being located along I-35.

There were three other Interstate Highways that I found with four capital cities along their routes.

• Interstate 20: Columbia, SC; Atlanta, GA; Montgomery, AL and Jackson, MS
• Interstate 40: Raleigh, NC; Nashville, TN; Little Rock, AR and Oklahoma City, OK
• Interstate 70: Columbus, OH; Indianapolis, IN; Topeka, KS; and Denver, CO

I-20 seems to offer a particularly good return on investment. The total driving distance would be a relatively compact 624 miles (1,000 km) along a nice route without the nail-biting traffic found in the northeast. I discovered a US Highway that also fit the bill. US Route 50 connects Annapolis, MD; Jefferson City, MO; Carson City, NV and Sacramento, CA.

Looking at pairs, which two are the closest together?

• Interstate 95: Boston, MA to Providence, RI (50 mi/80 km)
• Interstate 93: Boston, MA to Concord, NH (68 miles/110 km)
• Interstate 89: Concord, NH to Montpelier, VT (118 miles/190 km)

Another non-interstate, US Route 13, also does remarkably well with Dover, DE to Trenton, NJ (113 mi/182 km)

And the most frustrating? Denver, CO and Harrisburg, PA are both on Interstate 76. Hartford, CT and Boise, ID are both on Interstate 84. However, one cannot drive contiguously using the same highway between the pairs. The segments, despite common numbering, are separated by thousands of miles.

This was a fun albeit completely unproductive way to spend an entire evening.