I've seen threads on here that name examples of small localities being control cities that probably could easily be passed over (usually in New Mexico and Pennsylvania), but what about mid-sized cities that are large enough that aren't control cities? Here are some mid-sized cities that, in my opinion, could potentially be given control-city status.
Yuma, AZ - I-8 West: From the beginning of I-8 in Casa Grande all the way to the coast, the control city on I-8 West in San Diego. I think Yuma would make a more logical control city for I-8 West until the California border. I know some people like far-off control cities, and I prefer them over a minor locality if a decent-sized city isn't nearby. However, Yuma has a metro population of ~200k people and is the largest city in Arizona outside the Phoenix and Tucson metro areas. Yuma is also approximately the halfway point between Casa Grande and San Diego, making it a logical control point. Plus, the smaller Flagstaff is a control city on both I-17 and I-40, but likely is only granted control city status because of its interstate junction, which Yuma doesn't have.
Bridgeport, CT - I-95 South: New Haven makes the most sense as the control city for I-95 North out of NYC, as it's an interstate junction and a fairly recognizable city. In fact, Bridgeport wouldn't even be on this list if it weren't for a couple of small factors. First off, Bridgeport is the largest city in the state, yet isn't a control city, which feels strange to me. Although it's not too much larger than New Haven or Hartford. More importantly, the control city at the I-95/I-91 junction is New London, which is significantly smaller than Bridgeport. If New London is big enough to be a control city, than Bridgeport definitely is too. In this case, Providence or Boston would make more sense for I-95 North out of New Haven.
Manchester, NH - I-93 North: Out of Massachusetts, the control city for I-93 north is Concord, rather than the larger and closer Manchester. Similarly to Bridgeport, Manchester is the largest city in its state and is not a control city. I think the idea here is that people are more likely to be familiar with Concord, since it's the state capital. Still seems awkward for the largest city in the state to be passed up as a control city though.
Provo, - UT I-15 South: I can understand why Provo isn't used for I-15 North in Vegas, since Salt Lake City is much more well-known. However, Ogden is used for I-15 North. I think if they are going to use Ogden for I-15 North, they should use Provo for I-15 South. The only reasons I could see Ogden being used and not Provo is that Ogden is the largest city on I-15 north of Salt Lake City and there's a junction with I-84 in nearby Riverdale. Still, it feels a little odd seeing Provo being left out, as it's larger than Ogden. It should at least be co-signed with Las Vegas.
Bellingham, WA - I-5 North: The control city on I-5 north of Seattle is Vancouver, BC. While signing an international border is important, the border itself is still over 100 miles away. Like Yuma, Bellingham also has a metro population of ~200k and could certainly be used as a control city without a problem.