Museums including the National Portrait Gallery in Washington, D.C., the Metropolitan Museum of Art in New York City and the Art Institute of Chicago have portraits. Some portrait exhibits are viewable online, such as "American Origins, 1600 - 1900" and, from March 2015 to January 2016, "Elaine de Kooning: Portraits."
The Metropolitan Museum is exhibiting the portraits of John Singer Sargent from June 30, 2015 to October 4, 2015.
The Met and The Art Institute of Chicago have online collections of portraits and other artwork.
Art galleries and blogs are other places to view portraits. The Portrait Society Gallery of Milwaukee, Wisconsin has portraits in its blog as well as in the gallery.