Update XXI: "Scientific Facts Are Not Hard And Fast Rules."

[Linus Van Pelt]

Yeah, there are taxi companies everywhere. If you Google either "Oklahoma City taxi" or "Tulsa taxi" you get multiple hits for each, suggesting that there are various companies in each place.

Now, what is true in, say, Madison, and likely also Oklahoma, is that they're uncommon enough that you have to call one, and that if you just randomly go into the street in the hopes of hailing a cab like in a large city, you'll have no hope. But that's presumably also true in a British small town.

[Linus Van Pelt]

Actually cities are more spread out in the south.

[Linus Van Pelt]

"When dining out at a restaurant, how much do you usually tip for good service?"

15% or less:
nationwide 44%
Northeast 29%
Midwest 52%
South 49%
West 51%

more than 15%
nationwide 56%
Northeast 71%
Midwest 48%
South 51%
West 49%

http://michelinmedia.com/news/survey-american-diners-finds-tipping-habits-vary-considerably-demographic/

So, the Northeast is a bit inflated here.