A 306-seat, $42.4 million public pre-K center is expected to open in Flushing Meadows – Corona Park, Queens, by the fall of 2021, bringing much-needed relief to the overcrowded areas of Elmhurst and Corona, Mayor Bill de Blasio announced Thursday.

The new pre-K center promises to offer 4-year-olds a science, technology, engineering, art, and math curriculum — sometimes called STEAM — that will be run in partnership with the New York Hall of Science. Pre-K families will also get free memberships to the popular Queens museum.

It’s the first program of its kind to focus on early childhood science and technology education in collaboration with a major cultural institution, city officials said.

The center will participate in the education department’s “diversity in admissions” program to ensure that District 24’s “emergent multilingual learners” and students from low-income families are represented. The community will determine the specifics of the admissions priorities.

“It promises to be a program… that will be a true reflection of our community,” said State Sen. Jessica Ramos. “Many times communities of color like ours don’t think these STEAM careers of the future are for us.”

The new center is being built atop a parking lot in Flushing Meadows, but because the lot sits on parkland, it required Albany’s approval, and Ramos helped pass a bill to get the project done.

Officials agreed the process to approve the project has been a difficult one, and the 2021 date comes two years after it was originally scheduled to open, according to a previous report from DNAinfo.

As the community awaited the new pre-K center, the education department opened roughly 300 pre-K seats in September 2016 to meet the demand of the overcrowded District 24. Most of those new classrooms were in trailers, and served students at Corona’s P.S. 7, P.S 28 and P.S. 16, the report noted.

Those trailers will remain in use until the new pre-K center opens, and then those schools will get new outdoor play spaces when the trailers are removed, education department officials said on Thursday.

“Queens lacks seats that are required for the number of children,” Queens Borough President Melinda Katz noted. “We are exponentially growing in population and tourism and all that comes with it.”

The new center will be among the largest education department-run pre-K programs — opened across the city as part of de Blasio’s ambitious pre-K expansion. Universal pre-K for the city’s 4-year-olds across the five boroughs as well as free pre-K for 3-year-olds in several districts are the centerpiece of the mayor’s education agenda — as well as his overall legacy.

“How do we become the fairest big city in America?” asked de Blasio at the ceremony breaking ground for the center. “It starts the very first day a child steps in the classroom.”

He touted that the city has seen some benefits from free pre-K in the state test scores of last year’s third graders, the first group to participate in the universal pre-K program. The third graders in the program outperformed their peers and saw narrower gaps in scores between white and black students, as well as white and Hispanic students.