Anne Arundel County announced one of the strictest mask mandates in the Washington region on Thursday as leaders across the area monitor new coronavirus caseloads that have ticked upward this week.

The seven-day average of new cases in the District, Maryland and Virginia has risen daily since Monday, when the three jurisdictions were averaging 970 new cases. By Thursday, the region’s rolling average stood at 1,081 — on par with mid-June, when a sharp drop in cases began to stall.

Even as the number of cases has increased in recent days, other key metrics are holding steady or continuing to trend downward. Local officials are monitoring the mixed results and urging caution among residents as restrictions are lifted and other states see record surges in cases.

In Anne Arundel, the new mandate requires people to wear masks in outdoor public spaces when social distancing isn’t possible.

Nilesh Kalyanaraman, the county health officer, said he signed a public health order making masks mandatory to prevent the county’s rate of transmission from increasing.

Kalyanaraman said Anne Arundel, home to Annapolis, reports about 20 to 30 positive cases each day but has recently seen a “slight uptick” in its daily caseload.

“Now is the time to redouble our efforts to push down the number of cases per day and to focus on prevention,” he said as he illustrated the proper placement of a face covering over the mouth and nose.

The order goes beyond the state requirement, issued by Gov. Larry Hogan (R), for masks to be worn inside retail establishments, restaurants and grocery stores.

Kalyanaraman said the county will work with the police department to enforce the order. Residents initially will be issued a warning and given a mask, as well as information about preventing virus transmission.

County Executive Steuart Pittman (D) said the county will also boost enforcement of mask-wearing and social distancing in bars and restaurants. Health officials said they receive as many as 10 calls a day about businesses that might not be in compliance.

“We cannot allow the actions of a small number of irresponsible business owners to cause an industry-wide shutdown like we’ve seen in other states,” Pittman said.

The order comes as many states across the country experience surges in coronavirus cases. New Jersey Gov. Phil Murphy (D) took similar action Wednesday because, he said, the state had seen a “backslide in compliance.”

Virginia, Maryland and the District require masks to be worn in indoor public places, including restaurants, beauty salons, retail establishments and grocery stores, but Anne Arundel County’s mandate, similar to Montgomery County’s, is among the strictest in the region.

Lynn R. Goldman, dean for the Milken Institute School of Public Health at George Washington University, said that such measures have helped the region make progress against the virus but that the pandemic is “going on longer than we’re programmed to handle any crisis.”

Goldman, who is also a pediatrician and epidemiologist, said the District’s virus transmission rate is hovering at 0.9 percent — meaning every positive case, on average, is responsible for less than one other infection.

New York has lowered its rate of transmission to a range of 0.5 or 0.6 with restrictions in place, she said, but much of the United States hasn’t been “willing to put in place stringent-enough measures” to get in front of the virus.

Measures in the District have helped, she said, including having hospitals ramp up their number of beds, increasing the rate of testing and boosting contact tracing. But Goldman cautioned that the District has seen lower caseload reductions than some jurisdictions outside the region, even though local officials have “tried very, very hard to reduce transmission.”

For Washington, she said, it’s a struggle to decrease transmissions because the city is a hub of commerce and travel.

“We have a lot of essential activities that go on in D.C., regardless of what’s going on,” Goldman said, noting that the federal government and congressional offices continue to operate.

Goldman said the national capital region has done well in its response, but she worries more about Virginia than Maryland or the District, partly because the state has moved more quickly than its neighbors to reopen. So far, a recent increase in Virginia cases is concentrated in the Hampton Roads area, while cases in Northern Virginia have held steady.

Virginia entered its third phase of reopening on July 1. Maryland and the District have announced no timetable to make the leap into their Phase 3 plans, which relax restrictions more than Virginia did at that stage.

“We’re already starting to see that Virginia is moving in the wrong direction,” Goldman said. “There just isn’t a lot of room for error in this.”

Virginia Health Commissioner Norman Oliver said the state’s Washington suburbs have been successful in tackling the virus’s spread. He urged Virginians to remain vigilant, noting the state has avoided spikes seen in other parts of the country.

“Northern Virginia presents the best comparison to other parts of the national capital region, and has seen significant declines in case numbers, hospitalizations and percent of positive tests over the past month,” he said in a statement. “We are continuing to closely monitor health metrics across other parts of the Commonwealth, which tend to be closer — both physically and demographically — to our neighboring states of Tennessee, North Carolina and West Virginia.”

The number of recent ­virus-related deaths has changed little in the greater Washington region — although numbers are down in Maryland, steady in the District and up slightly in Virginia when compared with mid-June.

In Maryland, the seven-day average of daily deaths stood at 11 on Thursday, less than half the number in mid-June. The District’s average number of deaths is mostly unchanged at about two, while Virginia’s average has risen from about 11 to 17 during that time, with the increase generally coming outside the Washington suburbs.

The number of patients hospitalized with covid-19 in the region — which stood at 1,454 on Thursday — has trended downward since mid-June, as has the number of patients in intensive care or using ventilators.

Maryland officials said the state is continuing to make progress in battling the virus. Hogan said, “Key health metrics continue to trend in a very positive direction.”

Prince George’s County Executive Angela D. Alsobrooks (D) said Thursday that the Washington suburb, which was one of the hardest-hit in the region, continues to see infections and deaths trend downward. But she and the top health officer in Prince George’s warned there has been a slight uptick in recent days in the infection rate.

“Please remain vigilant,” Alsobrooks said at a news conference. “We are going to recover together, and we are going to do so with data and science.”

Alsobrooks said about 10,000 tests are being conducted weekly across the county, which is continuing to add new testing sites. She said positivity rates are down from their peak of 43 percent in late April to 6.5 percent in the last week of June.

Alsobrooks said the county hopes to continue to expand testing sites and will open a new site at a community center in Clinton next week.

Prince George’s County Health Officer Ernest L. Carter said the county has seen eight consecutive weeks of declining new cases and a steady reduction in how many Prince George’s residents have died of the virus. But he noted that covid-19 continues to be one of the leading causes of death in the county, and that the county’s infection rate recently ticked up to 0.92 after hitting a low of 0.72, which he said puts residents at “medium risk of spread.”

“We want to be clear: It is no time to relax,” he said. “Our cautious reopening approach has helped us get to this point. We should remain cautious.”

Carter said officials will respond appropriately if numbers begin an upward trend. He urged residents to answer their phones if contact tracers call them, saying contact tracing is a vital part of keeping infection rates low.

The District, Maryland and Virginia on Thursday added 1,236 known cases and 49 deaths, both above the region’s seven-day average.

The District reported 37 known cases and four deaths. Virginia added 613 cases and 32 deaths, while Maryland reported 586 cases and 13 new fatalities.

The three jurisdictions have recorded 5,793 coronavirus-related deaths and more than 150,000 known cases since the start of the pandemic.

The pandemic’s continued economic toll was clear Thursday as more than 68,000 people filed for unemployment claims last week in Maryland, Virginia and the District.

In the District, 2,538 people filed for new claims for the week ending July 4, down slightly from a week earlier. Virginia had more than 33,069 new claims, while Maryland had 32,497.

More than 1.5 million people have filed for unemployment benefits in the three jurisdictions since the pandemic began in the spring.

Laura Vozzella and Julie Zauzmer contributed to this report.