The other teams are based in Boston, Chicago, western New York, New Jersey, Kansas City and Washington, D.C.
The season is expected to start in March or April and conclude in September or October.
Portland Timbers owner Merritt Paulson will also invest in the women's league. He said Wednesday that the Timbers are pleased to do their part to help establish a top-flight women's league in the United States.
Paulson says the new team's name and logo will be released in the coming weeks.