NEW YORK (REUTERS) - New Jersey adopted a stringent coronavirus face-mask order on Wednesday (July 8), and New York City unveiled a plan to allow public school students back into classrooms for just two or three days a week, as Covid-19 cases soared elsewhere in the United States.

Officials in New Jersey and New York, the hardest-hit states at the outset of the US outbreak, want to preserve progress against the virus in the face of its resurgence elsewhere, primarily the US South and West.

More than 47,000 people have perished from Covid-19 in the two north-eastern states, accounting for more than a third of the US death toll of more than 132,000, according to a Reuters tally.

More than 60,000 new Covid-19 infections were reported across the United States on Wednesday, the greatest single-day national tally of cases yet since the virus emerged late last year in China.

New Jersey Governor Phil Murphy unveiled an executive order requiring face coverings outdoors where social distancing was not possible, saying the measure was necessary because of a rise in the state's coronavirus transmission rate.

"Wearing a face covering, I remind you, is not about politics. It's about quite simply being sick or healthy. It's about life and death," Murphy, a Democrat, said at a briefing.

Many states require masks in public indoor settings and recommend them outside, but have stopped short of mandating their use outdoors.

"I think that's the right thing to do," said Jordan Grant, 23, a real estate accountant who expressed dismay at seeing groups still congregating outside restaurants or at backyard barbecues without masks. "It's what we should have been doing months ago."

Republican state Senator Mike Doherty, however, accused the New Jersey governor of "exploiting a public health crisis for power", calling the new mask directive "oppressive".

In New York City, Mayor Bill de Blasio announced a plan for 1.1 million students in the nation's largest public school district to return to classes in September. Pupils would alternate attending school two or three days weekly and spend the remaining time at home.

'BACK TO SCHOOL'

Republican President Donald Trump, who has exhorted Americans to return to their daily routines, threatened to cut off federal funding to schools that fail to reopen on their normal schedule due to the coronavirus outbreak.

States are chiefly responsible for primary and secondary education, but the federal government provides some supplementary funding.

Vice-President Mike Pence said the US Centers for Disease Control and Prevention would soon issue new back-to-school protocols after Trump criticised current recommendations as too strict and costly. But Pence stressed that CDC guidelines are advisory.

Coronavirus cases have been on the rise in 42 of the 50 states over the past two weeks, according to a Reuters analysis.

The percentage of people testing positive among those who are screened has climbed above 5 per cent- to levels health experts deem concerning - in some two dozen states.

On Tuesday, the number of confirmed US cases crossed the 3 million mark, roughly equivalent to 1 per cent of the population and about 25 per cent of all known infections worldwide.

Democratic presidential candidate Joe Biden, who faces Trump in a Nov 3 election, described the grim milestone as "awful" and "avoidable".

He accused Trump of putting the nation in a precarious spot by not ramping up testing and deliveries of protective equipment.

The virus, which first surfaced in China late last year, is sweeping through a number of heavily populated states, including California and Texas, both of which reported their highest daily toll of Covid-19 deaths to date. Twenty states have reported record increases in cases this month.

PANDEMIC AND POLITICS

Houston, the largest city in Texas and the US oil industry's hub, registered more than 1,000 new cases on Tuesday, a single-day record, Mayor Sylvester Turner tweeted on Wednesday, calling the spread "severe and uncontrolled."

Turner, a Democrat, ordered the cancellation of a Texas Republican Party convention scheduled for July 16-18 in Houston, citing public health concerns.

In neighbouring Oklahoma, Dr Bruce Dart, the top health official in Tulsa, said Trump's campaign rally at an indoor arena in the city last month likely contributed to hundreds of new coronavirus cases over the past few days.

White House spokesman Kayleigh McEnany said she had seen no data to support Dart's conclusions.

An outbreak at the Mississippi state Capitol in Jackson left 26 lawmakers and 10 others infected, prompting the governor to urge anyone who had contact with a legislator to get tested, the Mississippi Clarion Ledger reported.

The surge has forced authorities to backpedal on moves to reopen businesses, such as restaurants and bars, after mandatory closures reduced economic activity to a virtual standstill in March and April and put millions of Americans out of work.

In Arizona, one of the latest epicentres of the US outbreak, 91 per cent of all adult intensive care unit beds are occupied, the state health department said on Wednesday.