The agency now urges all domestic travelers to "consider getting tested as close to the time of departure as possible (no more than three days) before your trip," according to its Covid-19 website updates this month.
This advice notably includes travelers who are current with their vaccines and boosters.
Previously, the recommendation to test before domestic travel applied to those who weren't up-to-date with their Covid-19 vaccines.
There's also testing guidance for after your trip is over, especially if you've been spending time in areas crowded with people.
The CDC recommends taking a Covid-19 test after domestic travel "if your trip involved situations with greater risk of exposure such as being in crowded places while not wearing a well-fitting mask or respirator."
Finally, the agency reminds travelers to be aware of local rules and conditions wherever they're going within the United States. Don't assume what holds true in your town or state is the same somewhere else.
The CDC advises people to "follow all state, tribal, local, and territorial health recommendations and requirements at your destination."
Different rules for international travel
These domestic updates are separate from CDC guidance for those traveling to the US, including US territories, from abroad.
Those travelers must have a negative coronavirus test within a day of travel or submit proof that they've recovered from Covid-19 in the previous 90 days. Children younger than 2 do not need to test.
The CDC also recommends getting tested three to five days after international travel to the United States.
Additionally, foreign citizens must be vaccinated for Covid-19 to enter the United States. No such requirement exists for US citizens, US nationals, and lawful permanent residents traveling domestically or internationally.
Still, the agency recommends that people be up-to-date with vaccines before any air travel.