FYI online pass are three / four months in advance. Just went to Smithsonian Museum Washingtonian D.C. this month. After 1 P.M. still had fun
Go online to the museum website. Groups 10 or more you can reserve a day for the passes. If you live in maryland D.C. virginia area its better to walk up monday-friday after 1p.m. you will not have a problem getting in. Or everymorning you can go online and reserve same day pass at 6:30 a.m. be ready to do that quick they go fast. Walk up best option. Or group of 10 or more.
Go to the website and select the day you are trying to visit. Keep in mind that there are a limited number of passes each day.
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