Also in San Francisco, the Cablecar Museum http://www.cablecarmuseum.org/
National Underground Railroad Freedom Center in Cincinnati. Never actually been there but the city is proud of it.
Wright Patterson Air Force Museum in Dayton Ohio.
American Sign Museum in Cincinnati.
The WWI Museum was really impressive.
Another gem in KC: www.1856.com. It’s about a ship, the Arabia, that was heading west with supplies for west-bound pioneers, and sank with all its cargo. Really interesting story about how the boat was found and the artifacts are stunning. You walk into the museum thinking it’s a ripoff and become engrossed in the story.
Then go out for ribs. The next day, if you’re a quilter, MSQC is a little over an hour away.
^^ The best attraction in NJ! Also recommend the Tenement Museum in NYC.
Karpeles Manuscript Library Museum, Tacoma Wa. VERY small, but rotating original documents, letters, etc.
Love the Dayton Airforce Museum…definitely NOT small!
If you are ever in Japan I highly recommend the Hiroshima Peace Memorial Museum which covers the atomic bomb attack of WWII. It’s very well done.
https://en.wikipedia.org/wiki/Hiroshima_Peace_Memorial_Museum
LeMay in Tacoma WA:
https://www.americascarmuseum.org/
I am not into cars, but I thought it was amazing.
The Great Lakes Shipwreck Museum in Paradise, MI. It’s remote and only open in the summer, but it’s fabulous: informative, a little creepy, and beautiful. The Edmund Fitzgerald was lost not far from the museum, and its bell is on display at the museum.
The museum sits on the shoreline of Lake Superior, which is gorgeous. You can climb the Whitefish Point Light Tower (the oldest lighthouse on Lake Superior), and you can even spend the night in the refurbished Crews Quarters, which is supposedly haunted.
I wouldn’t consider either The Clark or Mass Moca “hidden” but another lovely site in the Berkshires and right near the Norman Rockwell Museum is Chesterwood, the historic home and studio of Daniel Chester French, the sculptor of the Lincoln Memorial and there is a small museum there as well.
The Lincoln Memorial reminds me of another great site in DC, The National Building Museum where I once saw an exhibit about how the Lincoln sculpture was installed along with some other great exhibits and awesome space.
Other nice museum and the first two are for those planning trips to Maine,
Ogunquit Art Association
Portland Art Museum
New York Historical Society
The Jewish Museum (NY)
Museum of Quebec History (Quebec City)…
People have already mentioned Museum of the City of NY and The Morgan
ICA - one in Philly and another one in Boston
The Rose Art Museum (on campus at Brandeis University)
RISD Museum (Providence)
I also am a fan of the Peabody Essex Museum
The Mini Time Musuem in Tucson Arizona is awesome. All minitures. Doll houses, mini streets scenes, thumb nail sized portraits…it sounds kind of ridiculous but it was fascinating.
Here’s another in northern NE - home, studios and gardens of Augustus Saint-Gaudens in Cornish, NH which was an art colony frequented by many famous artists. It’s a national park site and a beautiful setting.
University of Pennsylvania Museum of Archaeology and Anthropology is really interesting.
National Museum of Women in the Arts – in DC, not part of the Smithsonian – https://nmwa.org/
Taliesin, Frank Lloyd Wright’s home, school, studio, and estate near Spring Green, Wisconsin.
Gilmore Car Museum in Michigan. It’s terrific!
Detroit Institute of Art. The collection is amazing, and it was well worth fighting to save when Detroit went through bankruptcy.
The Warhol Museum in Pittsburgh.
Cell Block 7 prison museum in Jackson sounds interesting, but I haven’t been there.
I loved the Hologram Museum in Chicago, but it’s now closed.
National Museum of the US Air Force in Dayton Ohio.
The Pima Air & Space museum in Tucson:
Taliesin West in Scottsdale, AZ Wright’s winter home.
Frederick R Weisman Art Foundation in
Beverly Hills. CA (Truly a hidden gem–the estate home of a wealthy collector that showcases his wonderful collection of 20th century contemporary art. You need to make an appointment.)
Fruitlands Museum–a collection of museums–Shaker house and artifacts, Native American collection, Hudson River School paintings and Colonial primitive portraits, and the Fruitlands farmhouse that was the home for the failed utopian community founded by Transcendentalists Bronson Alcott and Charles Lane. Louisa Alcott of Little Women fame lived there briefly as a child. She wrote about her experiences in Transcendental Wild Oats. All the collections were brought together by Bostonian Clara Endicott Sears who purchased Fruitlands as a weekend home in 1914. It’s in Harvard, MA about 35mi from Boston.
Adding to @rosered55’s recommendation, Taliesin West in Scottsdale:
Bradbury Science Museum - Los Alamos, NM
Los Alamos Historical Musieum - Los Alamos, NM
USS Pampanito - San Francisco, CA
Air Force Flight Test Museum - Edwards AFB, CA
The entire town of Virginia City, NV