USA is a very big place, so I bet fibre (to ADSL) is unfeasible in many places.
Yet many of those places are on the electrical grid. Rural electrification turned out to be feasible.
Here at the Mountain Fastness, a largely rural county got a widespread fiber-to-the-premises rollout courtesy of the local electrical co-op, which created an ISP subsidiary and ran the fiber on its existing utility poles. They already have to maintain the poles themselves and access to them, so it was just a matter of hanging an additional line along each run.
There's an additional installation fee to get the drop to each building where a subscriber wants service, plus the equipment, of course; but after that you can get various plans at rates which are considerably better in bandwidth, reliability, and cost/bandwidth than local DSL options.
There are also some firms doing fixed wireless in the area for off-grid homes, since they can use the fiber network for backhaul.
Yes, it might be hard to justify running fiber out to a building on some giant farm in western Nebraska or something. But I suspect it would be feasible to run fiber to a sizable majority of on-grid homes, which would serve most of the US population.