The Design of the US Interstate Highway System (1944) [pdf]

At one point in time or another I have been on the entire length of I-35 from Duluth to Corpus Christi. Not as a mission, just happenstance over the course of years. Probably not on all the side loops, though. I don’t have a point. It is just interesting to think about one’s travels in terms of line coverage.

I35 going through Austin is a pain if you live there. The story has always been that the army built that segment and they didn’t care about stopping anywhere in in Austin so it more or less goes straight through town and has these horrible on ramps where you have about fifty feet to accelerate to freeway speed, merge into traffic, and try not to hit the containment wall or other vehicles. As an alternative they built a bridge over that section that bypasses the downtown altogether (best bet if your traveling through). When I lived there I would go miles out of my way to avoid that area.

It was also the home of the Texans can’t drive in snow meme. One day there was snow falling lightly, wasn’t even really getting the ground wet, and somehow it caused a seventy car pile-up.

Bizarrely when they have tornados and severe weather in that area of Texas they tend to follow I35 south and you’ll get a lot of damage within a mile or two of the interstate.

Another curious factoid about Interstates in Texas, which prides itself on the quality and extensiveness of its road network, is that there's no interstate highway between its capital city (Austin) and its largest city (Houston). How to modernize transportation between the two cities is a subject of endless debate in Texas.

Yep. There are two major "twin city" metro areas in the US (Dallas/Ft Worth) and (Minneapolis/St Paul), and I-35 goes through both.

Funny I just noticed the "second city" of both is two words and typically written with an abbreviation.

Also, it's impossible to talk about freeways without mentioning I-19, which is signed in kilometers because it seemed at the time like the US was ready to go metric, and the Bay Area's I-380 which is not quite two miles long. It would have been longer had the original plans not been cancelled, but not much longer. Even then it's longer than I-180 which is only one mile, but I like the example if I-380 more because it's so heavily trafficked and it's quite clear at the interchange with I-280 where it almost went on further.

I-19's metric signage and I-280 connect to an odd common thread, though: California, perhaps because of its size and historic isolation, has historically had its own way of doing things. This extends to freeways, where California retained its historic system of marking highways (post-miles) instead of adopting mile-posts as the federal government dictated. The difference there is slight, but there's a bigger difference: California did not, initially, number its exits. Instead they were known only by name. By the '80s they had started numbering all exits but in areas with older infrastructure, such as 101 through San Francisco, most exist are still unnumbered until something forces them to replace the signs. The decision not to number exits is perhaps partially because of the post-mile system in which mile numbers are somewhat less linear than mileposts, but probably more due to California's large set of US Highways which were upgraded to freeway condition (such as 101) and had not historically been numbered. Today this would be unusual, a US Highway updated to freeway infrastructure is more often designated as a freeway (see this happening with US-93 near Las Vegas becoming I-11), but California did it in a number of major places.

The "California Difference" runs deep. Traffic signal controllers in California are built to a different standard than in the rest of the country, for example (except a few states that later adopted the California system). Mostly it's first-mover advantage.

Interesting. I live in NM and always wondered how they managed to plow not one but two interstates right through the middle of Albuquerque. It has turned out to be a boon for the city I expect. It's very easy to get from one side of the city to the other and as one of the major cities on Route 66 (now I-40) Albuquerque certainly hasn't lost its prominence along that major east/west route.

I-90 in Mass is a big compromise.

It balances distance Boston-NYC and Boston-Albany (and points west). If you look at the straight line distances to NYC and Albany as compared to the I-90 route, both are ~30 miles from ideal.

95 was supposed to go to Boston too, it kind loops around, but doesn't have the three number name. Its hard to build highways through land thats already been developed, its very political:

Also of note, each highway seems to have its own wikipedia page. https://en.wikipedia.org/wiki/Interstate_95_in_Massachusetts

"The original plans called for I-95 to run through downtown Boston. The highway would have progressed from Route 128 and Readville, followed the Southwest Corridor, joined the Inner Belt in Roxbury, heading east, and joining the Southeast Expressway at South Bay, then north to the Central Artery at the South Station interchange with the Massachusetts Turnpike/Interstate 90, and connecting with the Northeast Expressway at the Charlestown banks of the Charles River.

However, due to pressure from local residents, all proposed Interstate Highways within Route 128 were canceled in 1972 by Governor Francis Sargent with the exception of Interstate 93 to Boston."

If I remember correctly (grew up in Connecticut, drove through MA a lot), I-90 does not go directly through Springfield, but, rather, passes by a couple miles to the north.

My guess would be that that figure was wireframed by a draftsman using drafting methods, and then a commercial artist traced it to produce the final figure. Draftsmen had methods ranging from mechanical drafting arms to measuring techniques that allowed them to produce very precise figures, and much of computer graphics, perhaps even to this day, emulates the style developed by technical artists such as draftsmen and technical illustrators.

Not too long after 1944 these kinds of figures could be produced automatically by pen plotters and photosetters, but I don't believe anything of this type was available yet in the '40s. However, as early as the '40s photosetters and other photographic techniques may have been used in reproducing these figures more easily than having an engraver produce them in metal. I don't think this was widespread though, it wasn't until the '60s that photographic reproduction became common (leading to the term "camera ready" still used by many journals today for the final draft).