Maestro U.S.A., MasterCard's point of sale debit unit, has added 150,000 cardholders as a result of a decision by Boeing Employee Credit Union to join the network.
The credit union, based in Seattle, is the nation's fourth-largest, with 192,000 members and $1.8 billion of assets.
Debit cardholders will get access to Maestro in September.
Through an agreement with a regional electronic banking network known as Accel, Boeing credit union's cardholders already are able to use their debit cards for retail purchases in the northwestern United States.
But Maestro will give the credit union members the ability to use the cards at hundreds of thousands of merchant locations outside the region covered by Accel.
"Many of our members live outside the United States and often travel throughout the world," said Shirley Harney, supervisor of electronic delivery services at Boeing Employees Credit Union.
"Our goal is to provide them with versatility and easy account access wherever they may be."