Home to fewer than 22,000 people, the county is best known for the Sun Valley ski resort, which draw a steady stream of skiers, outdoor recreation enthusiasts and owners of second homes from across the country – and is now making headlines for a coronavirus infection rate that is one of the highest in the world.

In fact, as of Tuesday one of the largest single coronavirus clusters in the country was in the sparsely populated Great Plains state of South Dakota, where more than 300 workers at a giant ­pork-processing plant in Sioux Falls became sick with the virus over the weekend.

While the total number of cases can seem more alarming in larger cities, for smaller towns the virus can be especially devastating both to their already overtaxed health care systems and fragile local economies. Many smaller towns are kept afloat by only a few major employers, and when they close the effects can be catastrophic.

The South

In the south, Louisiana has been especially hard-hit, with Orleans Parish, home to New Orleans, battling the eighth largest degree of infection in the nation. Three relatively rural counties in Georgia make up the rest of the top 10 counties list — a clear reminder that not only large urban areas are at risk.

While there is evidence that the rate of new cases and deaths is flattening out in Louisiana, the reality on the ground remains daunting. On Tuesday, the state health department reported 884 deaths and 21,016 positive cases across the state, with the virus now present in every one of Louisiana’s 64 parishes.

New Orleans alone has had 5,718 cases, and 244 deaths — with the contagion thought to have initially spread during the city’s Mardi Gras celebration in late February.

Georgia, too, is reeling, with 14,223 confirmed cases of coronavirus and 501 deaths, with most of the deaths, 71, coming from Dougherty County, which has fewer than 100,000 people.

Florida, where Governor Ron DeSantis faced criticism for being slow to shutter businesses and beaches during the lucrative spring break season despite having an ageing population at higher risk from Covid-19, has also become an epicentre.

More than 500 people have died from the coronavirus, according to health officials on Tuesday; more than 125 deaths have been reported in cosmopolitan Miami-Dade County.

The Northeast

Along with New York, New Jersey — its neighbouring state and home to many New York-bound commuters — has also been severely affected. On Sunday, state officials confirmed 3,219 new coronavirus cases, a 4 per cent daily jump but still the lowest percentage increase since the outbreak began, a sign that infections in the state might be starting to level out.

North of New York, Massachusetts is now the state with the third-most cases of coronavirus in the country, with 26,867 confirmed cases as of Tuesday.

Boston Mayor Marty Walsh said that his city was facing a surge in hospitalisations and that confirmed cases had doubled in the last week alone. Over the weekend, the city converted the Boston Convention and Exhibition Centre to a temporary field hospital, with 500 beds reserved for homeless patients and 500 beds reserved as overflow capacity for local hospitals.

The city is trying to stay on top of its ballooning caseload through widespread testing, with the mayor now promising testing available for every Boston resident.

Pennsylvania has also emerged as fertile ground for the virus, with more than 25,000 cases in the state.

But there is also reason for hope. The number of new coronavirus cases in Pennsylvania fell to the lowest level in two weeks on Tuesday, showing that the recent surge of infections was perhaps coming under control.

According to the state’s health department, there were 1,146 new coronavirus cases on Tuesday, much lower than the record 1,989 new cases reported on April 9 during what is now considered the state’s infection peak.

But while the number of new cases was down, deaths were not. The 60 new deaths reported on Tuesday not only raised Pennsylvania’s total to 584, they were a considerable jump from the combined 27 deaths reported on Sunday and Monday.

The Midwest

Urban and suburban areas across much of the Midwest, largely untouched during the first weeks of the virus’s US spread, have been hit hard in recent days.

In Indiana, US Vice-President Mike Pence’s home state, more than 120 deaths have been reported in the county that includes Indianapolis.

In Wisconsin, at least 1,700 cases have been confirmed in Milwaukee County, home to the state’s biggest city, with at least 94 deaths.

Early actions pay off in US west coast fight against the outbreak

Michigan is reporting 25,635 confirmed cases and 1,602 deaths, but 760 of those deaths — and 11,648 of the total cases — are in Wayne County, home of Detroit, Michigan’s largest city.

“What we have is a lot of sad news,” Detroit Mayor Mike Duggan said over the weekend.

On Tuesday, photos from the city’s Sinai-Grace Hospital showed bodies being stored in vacant hospital rooms and piled on top of each other inside mobile refrigeration units in hospital’s parking lot. Over the weekend, a makeshift hospital was erected downtown.

Detroit is one of the worst affected cities in the entire country: more than 6,800 confirmed cases, and a staggering death rate of more than 5 per cent. Residents are considered especially at risk since many did not have consistent access to comprehensive medical care even before the crisis, with 36 per cent of the population living under the poverty line; moreover, some — following a series of controversial water shutoffs begun in 2014 — have had no access to running water to maintain basic hygiene in the face of the pandemic.

In Illinois, Chicago, the country’s third-largest city, had recently been praised for its response to the virus, but is now running out of ventilators, and rushing to prepare its convention centre to house hospital beds.

Chicago is facing some of the worst infection rates in the nation, with 9,113 cases and 308 deaths as of Tuesday, according to city officials. Also on Tuesday, Heartland Alliance, a non-profit organisation that oversees shelters in Chicago for unaccompanied migrant children, reported that at least 37 of the 69 children housed at the shelters it monitors have fallen ill with the coronavirus.

Statewide, Illinois reported almost double the coronavirus cases Monday as it did a week ago and more than double the daily death toll — with 74 new deaths, after charting a six-day low on Sunday.

Great Plains

While coronavirus spreads across the country, officials in more rural states like Nebraska and Kansas, North and South Dakota, continue to battle over whether to issue stay-at-home orders statewide.

In Kansas, Governor Laura Kelly, a Democrat, had banned gatherings of more than 10 persons, including for religious services — only to clash with Republican legislative leaders when they moved to block it because of the coming Easter services. Only on Saturday did the Kansas Supreme Court uphold her executive order.

And even as South Dakota was becoming one of the nation’s newest infection hotspots, Governor Kristi Noem remained defiant, refusing to require sheltering in place.

As many as 70 per cent of her state’s residents could become infected, she acknowledged on Monday; however, she maintained: “The people themselves are primarily responsible for their safety. They are the ones that are entrusted with expansive freedoms.”