Since last week, the small, rural northwestern US state of Idaho has been racking up 500 new coronavirus cases a day -- a sign of the exponential spread of the disease across the country.

With just 1.8 million inhabitants, Idaho -- famous for its potatoes and meat processing plants -- is seeing a virus resurgence as it also sweeps through the US South and West.

Meanwhile, New York and the northeastern United States, where the epidemic first hit hardest, have succeeded in tamping down infection rates.

Before June 15, Idaho was reporting fewer than 50 new cases a day. On Sunday, it reported 550, and more than 700 cases last Thursday.

Measured by size of population, Idaho's infection rate over the past seven days has put it in eighth place nationally, right after big southern and western states like Florida, Louisiana and Texas, according to data from The New York Times.

Not since the start of the pandemic have so many hospital beds in Idaho been occupied by coronavirus patients -- 224 on July 15. In April, the maximum number of hospitalizations was 71.

The number of actual deaths from the disease remains low at one to four a day, but is still up from June, when it was only one per day.

"Very concerning rises in rural America which has far less hospital capacity, less ability to surge," tweeted Ashish Jha, director of the Global Health Institute at Harvard University.

Idaho's governor, Republican Brad Little, has on several occasions postponed a complete reopening of the economy, originally scheduled for the end of June.

But all shops and services, including nightclubs, are open -- with social distancing requirements.

Idaho's largest city Boise, the epicenter of the state's infections, on July 4 made wearing a mask in outdoor and enclosed public spaces obligatory.

But in other parts of the state, the idea of enforcing face mask usage has run into stiff resistance from locals, prompting health officials in the north of the state to back down, according to The Spokesman-Review newspaper. 

Anti-mask protests have played out across the rural United States as local authorities try to get people to cover up and curb the spread of the disease.

President Donald Trump insisted in an interview aired Sunday that he did not intend to issue a national mandate on mask-wearing, instead leaving that call to individual states.