Museum Day, a day each year on which hundreds of participating museums around the US offer free admission (for those who have gotten tickets in advance), is tomorrow, Saturday, September 24, 2011.
The event is sponsored and coordinated by Smithsonian magazine. From the website description:
In the spirit of Smithsonian Museums, who offer free admission everyday, Museum Day is an annual event hosted by Smithsonian magazine in which participating museums across the country open their doors to anyone presenting a Museum Day Ticket…for free.
You must order tickets in advance, which can easily be done online, for one of the participating museums, two tickets per household.
The venues page lets you search for nearby (or distant) participating museums by way of typing in an address, searching a Google Map, or using a drop-down menu to search by state.
For more (and information on the North American Reciprocal Museum Program), see my post on Museum Day 2010.
(Images above, some participating art museums in the NYC area: Morgan Library and Museum, Brooklyn Museum, Newark Museum)