A 143-unit, fully affordable project at 1990 Folsom St. broke ground Friday evening — the fifth 100-percent affordable project to begin its rise in the Mission District in a year’s time.

The project’s groundbreaking “represents another big step forward in keeping San Francisco’s future as a diverse, welcoming city that we all treasure,” Karoleen Feng, director of community real estate at the Mission Economic Development Agency, told about 100 community members at the site.

The Mission Economic Development Agency and the Tenderloin Neighborhood Development Corporation proposed the project in 2016 and expect it to be complete in early 2021.

In addition to the affordable units, the nine-story project will include 15,000 square feet of ground floor space that will house the longtime community organizations Galeria de la Raza, Homies Organizing in the Mission to Empower Youth (HOMEY), and the Felton Institute.

“On this project, you’re really pulling together the essence of the Mission,” said Amy Beinart, an aide in Supervisor Hillary Ronen’s office, about the use of the ground floor space.

The total projected cost of the project is $100 million. The two community nonprofit developers closed on construction financing only two weeks ago.

Since last June, the Mission has seen five fully affordable projects break ground, making this the most active period in affordable housing development in the neighborhood in recent years. The relief Friday evening was palpable: Only last April, the seven approved affordable projects — including 1990 Folsom — appeared to have stalled.

“Every one of these [groundbreakings] represents an incredible amount of hard-fought struggle,” Beinart said.

The moment was especially significant for Galería de la Raza, which was forced out of its longtime home at 24th and Bryant streets after its landlord doubled its rent and subsequently evicted the gallery. The gallery temporarily moved to a space at 25th and Valencia in December.

Mayor London Breed, who has appeared at nearly every affordable-housing groundbreaking in the Mission, said that her office is committed to purchasing two more sites for affordable development using the so-called “windfall” funds.

The mayor emphasized that 40 percent of the project’s units will be reserved for people living in District 9 through the Neighborhood Preference program. “Apply, apply, apply,” she said, noting that her office will be doing outreach to ensure people know how.

Roberto Alfaro, the executive director of HOMEY, said he used to visit the building, which housed bakeries throughout the ‘90s and ‘00s. His father “used to buy me pan in the morning time,” Alfaro said. “He was excited we were doing this.”