WASHINGTON (BLOOMBERG) - With the spread of the coronavirus accelerating across the US, cities in the country are tightening measures to curb the disease.

The US's second-most populous state Texas ordered residents to wear masks, reversing course as it reported its second-highest number of daily infections.

The state recorded 7,915 new cases, according to state health department data on Thursday (July 2). The growth rate of 4.7 per cent surpassed the seven-day average of 4.2 per cent.

As virus-related hospitalisations and fatalities increased, medical facilities in Houston and elsewhere are showing increasing signs of strain.

The city of Houston posted a 4.3 per cent increase in Covid-19 patients in intensive care, and at the current rate of expansion, the city's hospitals will have to tap a second tranche of so-called surge beds on July 14, according to the Texas Medical Centre.

In a reversal of his months-long opposition to such a mandate, Texas Governor Greg Abbott Abbott, an ally of President Donald Trump, on Thursday said the mask order applies to all counties with 20 or more virus cases. He also barred people from gathering in groups larger than 10.

The Republican governor has been under growing pressure from Democratic mayors and county leaders to crack down or at least grant them authority to mandate masks and other restrictions.

In Miami-Dade, Florida's largest county, the authorities are implementing a 10pm to 6am curfew and rolling back the reopening of movie theatres, arcades, casinos and bowling alleys, among other places of entertainment, Mayor Carlos Gimenez said in a statement.

The curfew order exempts essential workers including first responders and hospital workers.

Mr Gimenez said hospitals are observing an "uptick in patients, and our medical professionals are seeing a rise in 18-to 34-year-olds who are getting extremely sick", according to the statement.

Florida reported 169,106 cases, up 6.4 per cent from a day earlier, compared with an average increase of 5.6 per cent in the previous seven days.

In Chicago, travellers entering or returning to the city from states with surging cases are ordered to quarantine for 14 days, starting July 6, Ms Allison Arwady, public health commissioner, said in a statement on Thursday.

The order applies to states with a rate greater than 15 cases per 100,000 residents per day, over a seven-day average.

New cases and death rates in Chicago and Illinois dropped from their peaks and both entered Phase 4 of the state's five-part reopening plan on June 26.

New Jersey Governor Phil Murphy, meanwhile, doubled the state's outdoor gathering limit, to 500, starting Friday morning.

Outdoor religious services and political activities, such as demonstrations, have no cap. Indoors, the crowd maximum remains 25 per cent of a space's capacity, with 100 people at most.

Mr Murphy this week indefinitely delayed lifting a ban on indoor dining, which was to restart on Thursday, citing "knucklehead" non-distancing behaviour at New Jersey outdoor establishments and spiking cases nationally.

New Jersey reported 13,251 dead who tested positive for the coronavirus and another 1,854 fatalities with a probable but untested link.

Tennessee's Davidson County, which includes the city of Nashville, reversed course after reporting a one-day record for new cases and will close socially driven businesses such as event and entertainment venues, Mayor John Cooper said in a statement.

Restaurants can remain open but must cut capacity to 50 per cent from 75 per cent, he said, noting the rate of new cases fell while bars and eating places were at half capacity.

The city - a popular US tourist attraction - will operate under the rules for several weeks, he said.

The US Centres for Disease Control and Prevention forecast as many as 160,000 deaths by July 25, with 11 states expected to register more deaths in the next four weeks than the previous four.

The alarming rate at which the coronavirus is spreading in the US has prompted the US Chamber of Commerce, the National Retail Federation, the Business Roundtable and others to urge President Donald Trump to issue guidelines on wearing masks, a day after Trump offered limited praise for masks but suggested they needn't be required.

"Absent stronger measures to prevent transmission, communities across America risk another round of shutdowns, broad restrictions on non-essential activities, and irreparable economic harm," said the organisations in a letter sent to the president on Thursday.