The 14.2 percent drop in passengers equaled the percentage loss in December over the same month a year earlier. But it was less than the decline in October and November.
"Thanks largely to continued fare sales and restored passenger confidence in air travel, we see a steady upward movement in passenger traffic," said David Swierenga, chief economist for the Air Transport Association, the trade group for the major airlines.
The airlines carried 37.4 million passengers in January, compared with 43.6 million a year earlier.
Airlines cut ticket prices to get passengers on the planes. The ATA said passengers paid, on average, 16.1 percent less to fly within the United States last month than they did in January 2001. Fares for international flights were 14 percent lower.
"Airlines continue to offer deep discounts in order to recapture passenger traffic, Swierenga said.
Last year, the major airlines carried 547.7 million passengers, a decline of 7.7 percent over the 593.4 million who flew in 2000. That is only the second yearly decline since World War II, according to the ATA. The only other drop came in 1991, following the Persian Gulf War and during the nation's last recession.