Passenger traffic at U.S. airports remains far below normal, but growing vaccination rates and an improving economy are leading to pent-up demand for travel, experts say.

Where it stands: A year into the pandemic, domestic air travel is 55% below pre-pandemic levels, while international travel is down 71%.

• Delta Air Lines is the only U.S. carrier still blocking middle seats as a way to limit capacity (through April).
• Meanwhile, Emirates Air now lets Economy Class customers pay $55 per empty seat to avoid sitting next to a stranger.

What to watch: Surveys show there's a growing willingness to travel once the virus is contained, according to the International Air Transport Association.

• But government quarantines are "a showstopper," says the group's CEO, Alexandre de Juniac.
• Global airlines are pushing for countries to enact a standardized digital health pass that would allow travelers to present their vaccine or COVID-19 testing status before boarding.
• Over 130 countries today require a negative COVID test to fly.