A continuation of the Library Association of Portland, established in 1864, the system now has 19 branches offering books, magazines, DVDs, and computers.

[2] After Leland H. Wakefield began collecting funds door-to-door in 1863, the Mercantile Library Association was started on January 12, 1864, with subscriptions by Portland's merchant elite.

[3] Judge Matthew Deady was one of the early founders, with financial support coming from those such as Henry Corbett, William S. Ladd, and Erasmus D. Shattuck among others.

[4][failed verification] Harvey W. Scott served as the first librarian, part-time, at its first location on Stark Street in Portland.

[3] Deady was the president from 1874 until 1893, and found that fundraising was "like pulling teeth", calling the local establishment "closefisted narrow visioned millionaires" in 1888, also stating "The rich men of Portland will never do much for [the library] until they die, and maybe not then.

[5] The board debated whether to accept government support, with Deady arguing against, out of concern for the encroachment of political influence, and on the principle that citizens would place more value on something they themselves paid for, even if the payment were small.

[5] In 1897, board president George Henry Williams proposed that the librarian be empowered to remove materials deemed to demoralize people and disorganize society," an approach in keeping with common library practice at the time.

[5] The library declined an offer of a $100,000 donation from Andrew Carnegie in 1901, expressing "great pride" in Portland's ability to take care of itself; later, it did accept $105,000 in 1911 and $60,000 in 1912 to build branch locations.

While it was supported by public fund, its management was in the hands of LAP, a private non-profit organization, whose board membership was hereditary, passing from fathers and mothers to sons and daughters.

At the same time, the library systems did not seem to work so well, with branches being closed and open hours cut back.

On July 1, 1990, the LAP officially transferred ownership of the library buildings and collections to Multnomah County.

[1] There are more than 425,000 library card holders in the system that serves a population of over 700,000 people, the largest in the state.