Smithsonian American Art Museum

8th & F Streets NW, Washington, D. C.
The collection, which was begun in 1829, was first on display in the original Smithsonian Building, now nicknamed the "Castle". The collection grew as the Smithsonian buildings grew, and the collection was housed in one or more Smithsonian buildings on the National Mall.

Among the significant artists represented in its collection are Nam June Paik, Jenny Holzer, David Hockney, Georgia O'Keeffe, John Singer Sargent, Albert Pinkham Ryder, Albert Bierstadt, Edmonia Lewis, Thomas Moran, James Gill, Edward Hopper, John William "Uncle Jack" Dey, Karen LaMonte and Winslow Homer. 

Source: americanart.si.edu