US vaccination rates vary enormously by state.
In states with high compliance, like most of the northeast, about 3/4 of adults are fully vaccinated (and about 85% have had at least one vaccine).
In states with low compliance, like the south, about 40% of the population is fully vaccinated (and under half have had one vaccine).
It also varies within states. There is a direct correlation between Trump voters and vaccine refusal. So, for instance, counties in west Mississippi voted for Biden; they have 18+ full vaccination rates mostly in the high 40s to high 50s percentiles. Counties in east Mississippi voted for Trump; they have full vaccination rates mostly in the low 30s to low 40s percentile. It's even more pronounced in states like Alabama (where some of the very Trumpy northern counties have full vaccination rates at 18%) and North Dakota (where the Trumpiest western counties have rates as low as 11%).
Some of these places will be spared a bit because they're so rural. The ND county with the 11% vaccination rate has about 800 people in it, and it's almost exactly the size of Gloucestershire.
But not only are vaccination rates very low in some of these southern states, but healthcare is terrible (most of them rejected the medicaid expansion for political reasons), comorbidities are high (in some states, about 3/4 are overweight or obese), the social safety net is thin (they've cut off the covid unemployment benefits), and the skepticism about covid is very very high.
So there's no masking, either. In many states, the vaccinated don't have to mask but the unvaccinated do. But the percentage of people who refuse the vaccine but will wear a mask is vanishingly slim.
And lots of people don't believe covid is real, still. If you want to get really, really mad, read this: www.washingtonpost.com/dc-md-va/2021/07/06/appalachian-covid-deniers-nurses-virginia/