UPDATE: Officials tell NBC News the mandate will be extended. Read more here for how long and what travelers can expect.
Following surges in COVID-19 cases, the Transportation Security Administration twice extended the face mask requirement for airports, planes, buses and rail systems.
As case numbers have dwindled and other COVID metrics have improved in recent months, the TSA is set to lift the requirement on March 18.
While the mandate could be extended once again, it's unclear if that will happen.
The requirement has remained in place even after the Centers for Disease Control and Prevention announced a shift in COVID-19 guidance late last month, saying most Americans are safe without a mask in indoor settings.
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It was a dramatic shift from the previous guidance, which recommended masks in counties with substantial or high transmission, a category that covered the vast majority of the country. According to a metrics update Thursday, more than 90% of Americans live in areas of low or medium COVID-19 transmission, meaning masks aren't recommended.
The CDC currently advises masks only in areas listed as having high transmission.
Despite the change in guidance, the TSA opted not to lift the federal requirement.
"The mask requirement remains in place and we will continue to assess the duration of the requirement in consultation with CDC," a TSA official said late last month as the CDC change was announced.
Trade groups such as the U.S. Travel Association, American Hotel and Lodging Association and Airlines for America sent a letter to White House Coronavirus Response Coordinator Jeffrey Zeintz following the CDC announcement, urging the Biden administration to lift the mask mandate by its planned date and end other COVID travel restrictions.
In the letter, the groups said ending travel advisories, repealing the federal mask mandate and working with other countries to end travel restrictions are crucial to restoring the U.S. economy and workforce.
"Effective, risk-based policies can be reinstated at any time if new variants of concern emerge or the public health situation deteriorates," the letter read, in part. "It is now time for the administration to lead the country towards a new normal for travel and on a faster path to a full and even economic recovery."