Despite infrequent service and early morning and late-night arrivals and departures, Amtrak ridership hit an all-time high in the Twin Cities last year.

More than 120,500 passengers boarded or stepped off the Empire Builder at St. Paul’s Midway Station in 2012, an increase of 19 percent since 1997, according to a report issued Friday by the Brookings Institution.

The uptick in passengers locally mirrors a national trend. The carrier transported a record 31 million passengers last year, up 55 percent since 1997. Amtrak’s growth exceeded all other forms of domestic transportation during that time period, said Robert Puentes, a Brookings senior fellow and co-author of the report.

In compiling his report, Puentes and two other fellows looked at Amtrak service in 100 of the country’s largest metropolitan areas. Those urban centers, including the Twin Cities, generate 90 percent of Amtrak’s ridership.

The study found the highest ridership in the Northeast and on the West Coast, but routes of 400 miles or shorter saw strongest gains and accounted for more than 80 percent of Amtrak’s riders. Those routes also made a profit, the study said.

Routes of more than 400 miles lost money.

Cities with the largest growth rates included those that have short-distance connections with regional peers, receive capital upgrades within their metro area or somewhere along the route, or both. More than 20 cities doubled their passenger traffic, and cities such as Dallas, Austin, Texas, Phoenix, Tampa, Harrisburg, Pa., Oklahoma City and Boston tripled ridership, the report said. Another 12 doubled ridership, including Milwaukee.

While the Twin Cities saw a 20 percent gain, only 14 cities had a lower growth rate, or lost riders.

Puentes attributed the lower growth rate locally to having only one station for the entire metro area. He also cited Amtrak’s schedule. Westbound trains to Seattle and Portland, Ore., depart St. Paul at 11:15 p.m. Eastbound trains to Milwaukee and Chicago leave at 7:50 a.m.

Ridership rose from just over 101,000 in 1997 to 120,515 last year.

Overall, Puentes said, Amtrak is experiencing a renaissance because “states now have formalized relationships with Amtrak to upgrade tracks, operate routes and redevelop stations. The result is a new federalist partnership where Amtrak, the federal government and states share responsibility for the network’s successes and failures.”

Later this year, Amtrak will move operations from the current station on Transfer Road to the remodeled Union Depot in downtown St. Paul.