Washington, D.C., Mayor Muriel Bower has unveiled a list of 27 states deemed “high-risk areas” -- meaning those traveling from them must self-quarantine for 14 days if arriving in the nation's capital.

As part of the District's effort to contain the coronavirus pandemic, the quarantine requirement was officially announced via an order from Bowser on Friday that did not specify which states were affected. It defined “high-risk areas” as “locations where the [seven-day] moving average daily new COVID-19 case rate is ... 10 or more per ... 100,000 persons.” Maryland and Virginia are exempt from the order.

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See the list here:

Additionally, Bowser is encouraging residents to either stay in D.C. or only travel to areas with low case numbers.

"District residents are encouraged to take 'staycations,' to stay local, or only travel to places with low COVID-19 case counts, and to maintain physical distance from non-household members at all times," the order says.

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The order says the list will be updated every two weeks, with the next update scheduled for Aug. 20.

The order is in effect until Oct. 9, or until any date through which a state of emergency is extended, whichever is later.

The requirement does not apply to those who are only “traveling through” those places, either by driving through or passing through an airport. The order also provides an exception for essential travel, but in those cases, people are to self-quarantine and seek medical attention if they exhibit symptoms.

Members of Congress are exempt because their work qualifies as essential service, and the Washington Nationals have also been granted an exemption waiver, WTOP reported.

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The announcement came just after Bowser boosted the city’s mask mandate, requiring anyone 3 or older to wear a mask any time they leave the house and may come in contact with others. The order indicated violators could be fined up to $1,000.

Fox News' Morgan Phillips contributed to this report.