American paused their mileage expiration from March-June due to COVID-19. In July they started expiring miles again, unless you were under the age of 22.5.
But now they have had a change of heart. Their media relations team writes to me that,
“American Airlines will temporarily pause mileage expiration through December 31, 2020. Miles that expired since July 1 will be reinstated and miles that were set to expire through Dec. 31 will now expire on January 1, 2021.”
Most other US airlines, including Delta, JetBlue, Southwest, and United, no longer expire miles, but this is still a nice gesture!
@xJonNYC also notes that if you paid to unexpire your miles, you’ll get bonus miles to make up for it.