Thank you for contacting the National Museum of African American History and Culture. We recognize and apologize for the frustration you have experienced when attempting to reserve timed-entry passes to the museum. The National Museum of African American History and Culture has generated an unprecedented level of interest on a local, national, and global scale. Since its opening in September 2016, more than 3 million people have visited the museum. The demand for passes remains high, and indeed has escalated during the Spring break season. The museum is working through a backlog of group requests and has temporarily suspended the group reservation system until the backlog is successfully addressed.
Website
You can either call them or visit their website.
There is a group section on the website. I have not personally navigated this section and don't know what the requirements are.
They currently do not have a process for requesting group tickets as there is a high demand.
Check the website
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