WASHINGTON — Amtrak carried more than a million riders in the Northeast in April, the best performance for a single month in eight years, the national railroad said Wednesday.

Amtrak attributed the record-setting performance to a strong economy and “mounting disaffection with the quality of air service.”

Stan Bagley, president of Amtrak’s Northeast Corridor, said the company will have momentum when it launches high-speed service later this year between Boston and Washington. The “Acela” trains will be able to travel up to 150 mph.

The 1,073,564 riders was a 3.2 percent increase over April 1998.