Washington DC is the latest US municipality to implement an indoor mask mandate, and DC officials took it a step further and urged residents to wear a mask in 'large outdoor settings.'
The new mask policy will go into effect on July 31 at 5am and will require everyone over the age of two to wear a mask inside regardless of vaccination status.
The requirement applies to people who are not eating in restaurants, but sporting events like baseball games won't require a mask.
Masks are being reintroduced throughout the US as the highly transmittable Delta variant sweeps across the nation and now accounts for 83 percent of the country's COVID cases, according to the CDC.
Washington DC joins Kansas City, Savannah in Georgia and Los Angeles who already implemented indoor mask mandates, as did a few private companies including Facebook, Google, Netflix, Morgan Stanley and the Washington Post.
Workers in Clark County, Nevada, which includes Las Vegas, will have to resume wearing masks indoors. Customers will not be forced to, under new rules.
Scroll down for video.
Washington DC Mayor Muriel Bowser implement an indoor mask mandate that will go into effect on July 31
During a Thursday press conference, Mayor Bowser said the masks are being reintroduced because of the Delta variant
Washington DC has seen a 37.8 percent spike in the number of cases over the last week
Washington DC has seen a 37.8 percent spike in the number of cases over the last week, including several members of the the Washington Nationals baseball team.
The Nationals were forced to postpone their game Wednesday night after four players and eight staffers tested positive, and all but one were vaccinated.
Washington DC Health Director Dr. LaQuandra Nesbitt said during a Thursday press conference that there's been a 'five-fold increase' so far in July in the case rate.
Virus rates 'are skewing to the younger population,' Nesbitt said, and have increased for children age 5 to 14 and young adults age 20 to 34. The vaccine is only approved for ages 12 and up.
Many new cases have been linked to travel, dining out and social activities in large groups, she said.
Nesbitt said the vaccines 'are working as intended,' even when vaccinated people test positive for the coronavirus because the symptoms are milder and they don't need to be hospitalized.
At the US Capitol, police were originally been ordered to arrest visitors and staff who refuse to wear a mask on the House side of the Capitol complex, but the department reversed course after backlash from Republican lawmakers.
Many Republicans have opposed forcing people to wear masks and maintained their belief that masks are all about politics.
To settle tensions, US Capitol Police backpedaled on Thursday and said they would ask people in the House of Representatives not wearing a face mask to leave.
But the agency did not specifically rule out arrests but did say it should never come to that.
‘Regarding the House mask rule, there is no reason it should ever come to someone being arrested. Anyone who does not follow the rule will be aske to wear a mask or leave the premises. The Department’s requirement for officers to wear masks is for their health and safety,' US Capitol Police tweeted in a statement.
On Tuesday, the CDC updated its indoor mask guidelines to protect against the Delta variant's spread, but it's become a political lightning rod.
St. Louis County Executive Sam Page implemented an indoor mask mandate for ages of five and older on Monday but the county council made a sharp U-turn and rescinded the mandate in a contentious 5-2 vote on Tuesday night.
Residents spoke for hours against wearing masks before the vote, and the county's public health director - Dr. Faisal Khan - was bumped, pushed and called a 'fat brown c**t' and 'brown b*****d' after he spoke in favor of wearing a mask.
As the number of cases climb in the US, they're plummeting in the UK.
The daily number of new infections recorded in the country fell seven consecutive days before Wednesday's slight bump, when the country reported 27,734 cases, which is about half of the reported cases last week.
Meanwhile in the US, the CDC reported a seven-day average of 40,246 new cases, which is a 46.7 percent spike since last week.