Almost every major Texas city today has at least two "circular" or beltway highways: one around the downtown area, and another further out toward the edge of the city, with other highways acting as spokes on the wheel. The largest Texas cities all have more though:
San Antonio has the Downtown Circulator, I-410, TX-1604, and the makings of another circular route formed by TX46, 123, 97, and 173.
Houston has a Downtown Circulator, I-610, TX-8, and TX-99 (Grand Parkway).
Dallas and Fort Worth both have their own downtown loops and beltways as well.
Even smaller cities like Crockett, Lufkin, Carthage, Nacogdoches, Victoria, Abilene, Amarillo, and Lubbock all have ring-road systems.
I've tried looking at other states with similar geography and what I find is that some states have similar formations, but far less defined, while other places seem to be much more grid-based. I'm interested in learning about how highways in Texas were historically planned, and if any of that may have lead to the formation of what seems to me like wheel and spoke cities.
I hope that this is the appropriate place to post this question, since I'm interested in what historically lead to this development, but please let me know if there is somewhere else this question might be better located. Thank you in advance!
I don't have all the info, but I can get you started.
We call them 'loops,' as does the state department, but if you look into the technical definition according to the ones who build them, loops are not necessarily circular, but they are required to connect two state highways.
Often, to avoid traffic congestion in the middle of town, a loop or half-loop, or even a 3/4 loop would be constructed so thru-traffic could remain at or close highway speeds while bypassing the town. The loop would qualify by connecting one portion of the state highway (for instance, north of the town) to another portion of the same highway (south of the town). This technicality is why Austin's two loops are actually somewhat banana shaped, Loop 1, and Loop 360.
As the towns grew, the first loop would become inaffective, and a second loop would be added, again diverting unnecessary traffic just passing through out of the main thoroughfares.
In a glossery on txdot.gov a listing for "State Highway Loop" defines it as a... "Roadway usually created as a by-pass, so designated by the Texas Transportation Commission. "
Hints of this circular bypass method appear to be visible on maps of Tulsa and Memphis, and in Saint Louis, IH 270 wraps most of the way around the city, connecting several other major roadways.