OK, the UK has been doing digital terrestrial for many years now, and is currently in a gradual switch-off of the analogue transmitters.
The digital transmitters are all of considerably lower power than the old analogue ones, but coverage is supposed to be the same - they don't need as much power to give the same coverage.
As long as your analogue pictures were of good signal strength, and assuming it's using similar frequencies, then reception should be fine. All the UK transmitter details are freely available on the net, I can't see the USA ones aren't also available?.
An obvious (and simple) solution is to ask at a local TV shop, not a large multiple staffed by untrained kids, but a 'proper' small TV shop that knows what it's doing.