If you want, I'll keep going!
Interestingly, Wikipedia don't have an article for neither Buffalo or St. Louis.
About Buffalo, I've noticed they have a ring road formed by I-190, I-290, I-90, NY-179 and NY-5.
Regarding St. Louis, I checked quickly and we'll have to make some compromises on the edges. Several census tracts are bisected by it. It's possible to have a very close estimate though. Your population figure is probably right. Maybe a bit more. St. Louis county and city plus the two IL counties had 1,829,475 in 2020. As good chunks of the three counties are out of it I'd guess something around 1.4 million. And population inside that ring is falling in a quite fast pace.
EDIT looking closer to St. Louis, they have an inner ring, formed by 67, 61 and 50. This one matches perfectly with the census tract. We could cross the river with the road 3, but it seems almost no one live between it and the river.
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