The woman holding the Multnomah County Library card is Sarah Ann Long, Multnomah County librarian (that's the title used for the library director at the time).  I would hazard a guess that the other people are directors or representatives of the Washington County and Clackamas County libraries.  I couldn't say who the fourth person is!

Also. . .  it might be useful to add that the Metropolitan Interlibrary Exchange (MIX) agreement allows people who live in the participating library districts to get cards at all of the libraries.  As of 2017, the following libraries particpate in MIX: Camas Public Library, Fort Vancouver Regional Library District, Hood River County Library District, Library Information Network of Clackamas County and Washington County Cooperative Library Services. There is more information about the MIX agreement on Multnomah County Library's website: https://multcolib.org/library-cards-non-residents .

MIX was introduced in 1986, and during the pilot phase it went by the name "Access '86."