The Largest Science Museums In The United States
On November 13, 2026, a 20-story gallery built around the space shuttle Endeavour opens in Los Angeles, adding 200,000 square feet to the California Science Center and moving it past the Griffin Museum of Science and Industry in Chicago, which bills itself (for now, at least) as the Western Hemisphere's largest science museum.
Largest, for this ranking, means only one thing: the total floor area, in square feet, that each museum publishes for its main campus as of 2026. Only science and technology museums qualify, so the natural history giants in our list of the largest museums in the United States are out, as are air and space museums and children's museums.
1. California Science Center, Los Angeles, California
Floor area: 615,000 square feet
The Science Center says it's the only place in the world to see a complete shuttle stack in launch position. Its three galleries cover air and space travel, with a special emphasis on the shuttle program. The Shuttle Descent Slide, a 115-foot tube that drops 45 feet, returns visitors to the gallery floor. Entry to the museum is free, but the new wing requires a timed reservation.
The state-owned California Science Center opened in 1998 in Exposition Park, beside the Los Angeles Memorial Coliseum. State budget documents put the original building at 245,000 square feet, and the Ecosystems wing, which opened in 2010, added 170,000 square feet, for a grand total of 415,000.
But this already big number is set to change on November 13, 2026, when the Samuel Oschin Air and Space Center adds another 200,000 square feet. The new total sees the science center weighing in at a hefty 615,000 square feet. The new wing was built around Endeavour, which stands upright with its external tank and twin solid rocket boosters in place.
2. Griffin Museum of Science and Industry, Chicago, Illinois (Tie)
Floor area: More than 400,000 square feet
Julius Rosenwald, the chairman of Sears, Roebuck and Company, pledged $3 million to start this museum after a visit in 1911 to the Deutsches Museum, the science and technology museum in Munich, Germany.
The museum opened in June 1933 in the Palace of Fine Arts, built in 1893 for the World's Columbian Exposition in Jackson Park on the South Side of Chicago. The present name dates to 2024 and recognizes donor Kenneth C. Griffin.
The museum's more than 400,000 square feet of exhibits include the Coal Mine, its first exhibit, and U-505, a German submarine captured in World War II that visitors can board. A $10 million project to reopen the original south entrance is due for completion in 2027.
3. The Franklin Institute, Philadelphia, Pennsylvania (Tie)
Floor area: More than 400,000 square feet
Although not the biggest science museum on this list, The Franklin Institute does get an honorable mention for being the oldest. The institute was founded in 1824, and its current building in Philadelphia opened in January 1934 and covers more than 400,000 square feet of exhibit space.
Its signature exhibit is the Giant Heart, a walk-through model that reopened in 2024 as the centerpiece of its Body Odyssey gallery. The Baldwin 60000, a 350-ton steam locomotive, has been here since 1933, and the building also contains the Benjamin Franklin National Memorial. It also houses the Fels Planetarium, the second-oldest planetarium in the Western Hemisphere.
4. Science Museum Oklahoma, Oklahoma City, Oklahoma
Floor area: More than 390,000 square feet
What began in 1958 as the Oklahoma Science and Arts Foundation, housed at the state fairgrounds, moved to the Kirkpatrick Center when it opened in 1978 in a part of Oklahoma City that's now called the Adventure District. The museum gives its size as more than 390,000 square feet and describes itself as the state's only hands-on science museum.
A $22.4 million capital project completed in 2016 added a new atrium and entrance. CurioCity, a 20,000-square-foot children's area opened in 2015 and is larger than 95 percent of the stand-alone children's museums in the country, according to the museum.
The newest addition is Love's Planetarium, that opened in September 2024. The building also has more than 500 exhibits and a collection of more than 40,000 artifacts and documents.
5. Science Museum of Minnesota, Saint Paul, Minnesota
Floor area: 370,000 square feet
Opened in 1999 on the Mississippi River waterfront in downtown Saint Paul, the current building is the fourth home of a museum founded in 1907 as the St. Paul Institute of Science and Letters. Its 370,000 square feet covers the whole building and includes a 10,000-square-foot gallery for temporary exhibitions.
The museum says it's one of only four in the world with a complete Triceratops skeleton. Its Omnitheater opened in 1978 and was only the second IMAX dome theater in the world. The center's collections number more than two million objects. The National Park Service runs its Mississippi River Visitor Center in the museum's lobby.
6. Exploratorium, San Francisco, California
Floor area: 330,000 square feet (Indoor and outdoor combined)
Physicist Frank Oppenheimer founded the Exploratorium in 1969 at the Palace of Fine Arts in San Francisco. It relocated to Pier 15 on the Embarcadero, the city's waterfront boulevard, in 2013, moving to a campus three times the size of the original. Pier 15 was built in 1914 and rebuilt in 1930, and its shed is now the main exhibition hall.
The only new structure is the glass Bay Observatory at the end of the pier. The campus includes 1.5 acres of free public space, and the museum's workshop is on view to visitors, just as Oppenheimer had wanted. Pi Day, celebrated on March 14, started here in 1988.
7. COSI, Columbus, Ohio
Floor area: 320,000 square feet
COSI, short for the Center of Science and Industry, opened in 1964 and moved to its present building on the west bank of the Scioto River in downtown Columbus in 1999. It was created by joining a new 230,000-square-foot structure to the former Central High School, a 90,000-square-foot brick building.
COSI features more than 300 interactive exhibits in nine galleries, along with a planetarium and little kidspace, an area for children. Its Dinosaur Gallery is named for the American Museum of Natural History in New York. A fun outside attraction, the Big Science Park has a lever that lets visitors lift a 2,437-pound car.
8. Liberty Science Center, Jersey City, New Jersey
Floor area: 300,000 square feet
Opened in 1993 in Liberty State Park on the Hudson River waterfront in Jersey City, Liberty Science Center is close to the Statue of Liberty. The 300,000-square-foot building has 12 exhibition halls and a live animal collection of 110 species. The Jennifer Chalsty Planetarium, opened on December 9, 2017, has an 89-foot dome and is the subject of our look at the largest planetarium in the United States.
An expansion backed by $39.6 million in state tax credits has been approved and will add more than 100,000 square feet of outdoor exhibition space, including a river otter habitat, physics-themed mini golf, and a memorial garden with beams from the World Trade Center.
Contenders We Left Out
The Saint Louis Science Center in Forest Park is the biggest question mark. While it publishes no building total on its website, a figure of 382,000 square feet of exhibit space and grounds combined has been quoted elsewhere, while yet another source places it at more than 300,000. Either number would place it on this list.
The Phillip and Patricia Frost Museum of Science in Miami lists 250,000 square feet and comes next. The Museum of Science in Boston publishes no total, though its 10,000-square-foot Public Science Common opens on October 10, 2026.
Old Buildings, New Wings
Two museums on this list opened less than seven months apart in 1933 and 1934, respectively with both still in the buildings they opened in. The rest of the list is newer, with some looking at changes that would affect their placement on our list of the largest science museums in the United States. But for now, the ranking runs from 615,000 square feet in Exposition Park to 300,000 on the Hudson.
