You can get connections suitable for backhaul pretty much anywhere as long as you are within reach, or prepared to pay for, a copper or fibre connection to an exchange. It just costs more.

I'm not up to date on prices.

Backhaul is 'just' another connection but without the same contractual restrictions as you'll usually find on normal subscriber connections.

You'll find it used in at least two different ways: as a synonym of transit to talk about a way for your ISP to connect to any other ISP via the provider they get it from, and as a means of having an access provider forward last mile traffic to one or more central locations.

But in both cases it just suggests that you have agreed with a provider to forward traffic for your users on your behalf.