A number of U.S. airlines are considering relocating crew members from hotels in certain layover cities ahead of possible unrest following Tuesday’s election.

United Airlines sent a memo to flight attendants Friday detailing plans to move crew members from downtown-area hotels in cities including Portland, Seattle and Washington, D.C., amid the “possibility of renewed protest activity,” USA Today reported.

“In order to prevent any potential delays of our crewmembers getting to where they need to be on time, we have relocated some of our crews to airport hotels,” United confirmed in a statement shared with Fox News on Tuesday morning.

“We have also moved our Network Operations Center to a backup facility outside of downtown Chicago to ensure our operations continue to run on schedule,” the statement said.

PASSENGERS BOOTED FROM FLIGHT AFTER ONE ALLEGEDLY HIDES UNDER THE OTHER'S FIRST-CLASS SEAT

Crew members stationed in Atlanta, Denver, Chicago, Portland, Philadelphia and Seattle, as well as both Arlington and Dulles, Va., are expected to be among those relocated.

CHICAGO, ILLINOIS / USA - March 10, 2018: A United Airlines passenger aircraft - Boeing 777 - arriving at Chicago O'Hare International Airport on a sunny morning.

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Chicago-based United might not be alone: Delta Air Lines, American Airlines and Southwest Airlines also plan to relocate crew members as a safety measure, though none have confirmed whether that option was currently being exercised.

“Since nothing is more important that the safety and health of our people and customers, we do have the ability to shift our crew hotel sites if warranted,” Delta said in a statement obtained by Fox News.

“But out of many safety and security considerations, we don’t detail location or duration specifics,” the airline added.

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American and Southwest added that they, too, are prepared to change crew hotel plans as needed. 

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The possibility of post-election protests or rioting is a concern for both law enforcement agencies and citizens in cities across the United States.

A recent poll conducted by USA Today and Suffolk University found that three out of four voters are concerned about the possibility of violence on or after Election Day, with only one in four saying they were “very confident” that a peaceful transition of power would take place should former Vice President Joe Biden win.

Fox News’ Adam Shaw contributed to this report.