[3] It was founded following an informal meeting of 17 environmental advocates, including Bowdoin College professor John Rensenbrink and others in Augusta, Maine in January 1984.

Previously the Maine Green Party achieved ballot status in 1994 with the Jonathan Carter gubernatorial campaign, but lost it in 1997 after Ralph Nader failed to get 5% of the vote for president in 1996, a requirement of state law that has since been changed.

The campaign's website was indexed by the Library of Congress and won a Golden Dot Award, because of the site's use of new ways to interact with voters.

The party (in terms of registered votes) is currently in a period of continuous growth stretching back to 1998 according to state records.

From 2002 to 2006, the highest-ranking elected Green in the United States was John Eder, who served in the Maine House of Representatives for Portland's West End neighborhood.

[14][15][16] Four of the state's elected Greens are Portland officeholders, including three School Committee members, and one City Councilor.

[21] Trevorrow lead the 2010 campaign while also running for the East End seat in the Maine House of Representatives.

In the closing days of the campaign, Eder endorsed fellow candidate and former Democratic State Senator Ethan Strimling, not party member Marshall, causing significant controversy within the Greens.

In March 2013, the Portland Green Independent Committee took out petitions to enact an ordinance which would make marijuana legal for adults 21 and older, though not in public spaces such as roads, schools and parks.

[26] That same year, Anna Trevorrow was elected to an at-large seat on the School Board, joining Holly Seeliger.

In 2015, six Greens sought office in Portland, including committee chair and economic justice activist Tom MacMillan, who ran for mayor and received over 10% in a three-way race with Michael Brennan and Ethan Strimling.

In 2017, School Board member and YouTube vlogger Holly Seeliger was criticized for giving credence to conspiracy theories including Pizzagate and the Murder of Seth Rich.

She dropped out of the race after failing to receive enough signatures to qualify for the Green Independent primary ballot for governor.

Following Maine's enactment of Ranked Choice Voting for elections, the spoiler effect was eliminated as a barrier for third parties.

[35] That year, K. Frederick Horch, the Green nominee for the Maine State House's 49th district, also came close to winning his race, receiving 48.06 percent of the vote against a Democratic opponent, with no Republican on the ballot.