Seattle could have ended up looking a lot different, and transit advocates would have a lot more to worry about, if a coalition of concerned residents hadn’t stepped up 50 years ago.

The Seattle group Activists Remembered Celebrated & Honored (ARCH) is celebrating the 50th anniversary of Seattle’s Freeway Revolt with a community celebration and open house at the Central Area Senior Center 3-6 p.m. Sunday, Sept. 23.

The Citizens Against RH Thomson (CARHT) formed in 1968 to oppose a proposed expressway that would have gutted the Central Area.

The R.H. Thomson Expressway would have run from the south end of Martin Luther King Jr. Way to East Madison Street, and had the potential to connect up to State Route 520 by running along the western edge of Madison Park, and included an Interstate 5 interchange at Roanoke Street; I-5 was completed in 1967. The Thomson Expressway would have terminated at a proposed Bothell Freeway.

The state transportation department’s plans, which also included the Bay Freeway — a freeway that would have connected the Seattle Center to I-5 by running parallel to Mercer Street — and 14-lane Interstate 90 were not fully formed when work picked up in the 1950s. Voters approved bonds for the Thomson Expressway and Bay Freeway in 1960 — at $11 million and nearly $2 million, respectively.

A year prior, the Legislature approved taking back two blocks of the Washington Arboretum Park it had given to the University of Washington in 1939. Three incomplete ramps remain where the expressway would have connected to a second floating bridge. The replacement of the State Route 520 bridge will see two of those ramps removed, with one planned to become a park monument during WSDOT’s Rest of the West phase of construction, said ARCH member Anna Rudd, who lived in Seattle during the Freeway Revolt.

Rudd didn’t join CARHT immediately, she said, and had previously been involved in telephone trees that aimed to gather community opposition to the massive transportation projects.

She’s organizing the 50th anniversary celebration of Seattle’s Freeway Revolt with fellow ARCH member Allan Davis, who served on the CARHT board.

Rudd said CARHT was instrumental in getting people out to vote in 1969, which helped elect councilmembers who were also opposed to continuing with the controversial Thomson Expressway and Bay Freeway.

CARHT was led by chairman Maynard Arsove, a mathematician and civic activist, who passed away in 2010.

“Maynard, he was just, like, the totally perfect person,” Rudd said. “He’s very deliberate, he’s very thoughtful, he’s very kind. I don’t think I ever heard him raise his voice.”

The City of Seattle decided in 1967 that it would stop planning for a Thomson-I-90 interchange, but activists were not convinced the project wouldn’t proceed anyway.

Thousands gathered in the Arboretum on May 4, 1969 to march in protest of the R.H. Thomson Expressway.

The city council voted on June 1, 1970 to remove the expressway from its comprehensive plan, but proceeded with plans for a six-lane Bay Freeway, later approving construction for a partially elevated four-lane freeway.

CARHT was joined by seven other groups in filing a lawsuit to stop the freeway project. A superior court judge sided with the organizations in 1971, agreeing the design the city was pushing was much different than the one voters approved funding for in 1960.

Rudd said it was amazing to see all of the groups that came together to oppose these large transportation projects that would have negatively affected the Seattle landscape, including the Black Panthers, who saw the African-American community faced with being pushed out of the Central Area.

The city council scheduled a referendum for February 1972 that sought approval for the Bay Freeway, and another referendum to formally terminate approval of the Thomson Expressway, the latter approved by around 71 percent.

Rudd was also treasurer for Vote No Bay Freeway, which opposed Referendum 1. Voters opposed continuing with the Bay Freeway by 55 percent. Davis laughed when thinking about how the city had banked on voters approving the Bay Freeway, and foolishly spent $12,000 on publishing requests for proposals before the vote.

As commuters will notice, the 14-lane Interstate 90 was scaled down to just eight lanes in the end.

The Sept. 23 Seattle Freeway Revolt celebration will include informational displays about the history of the 20-year movement, an open mic for former activists to share their stories and a preview of a documentary about the revolt being developed by filmmaker Minda Martin. The Central Area Senior Center is at 500 30th Ave. S.

Find out more about Activists Remembered Celebrated & Honored (ARCH) at seattle-arch.org.