Autograph signatures, signed letters, and other signed pieces of artists vary in availability, and collector demand varies widely. The most popular area of interest among collectors is the French artists, beginning with early Impressionism in the 19th century and continuing well into the 20th century. Signed letters of Edouard Manet, the originator and leader of Impressionism, are, relative to other artists of the later period, much rarer and more in demand. Claude Monet was very well-known and signed many letters, but he is in great demand by collectors. More likely to be found are signed pieces by Auguste Rodin, the leading sculptor of realism. Pablo Picasso would give his autograph signature to admirers both through the mail and in person, but the international interest in Picasso has created a demand that has made his autograph signature difficult to find. The autographs of Henri Matisse, a leading fauvist painter and sculptor, are much rarer than the autograph material of his contemporaries. The Spanish surrealist Salvador Dali signed his autograph under many different circumstances but his popularity has caused him to not be as common as he might be.
In the field of American art, John James Audubon’s autograph signatures and signed pieces are quite rare. The sculptor Augustus Saint-Gaudens less so, but his signed letters have been collected by an institutional library. John Singer Sargent, who wrote many signed letters of a social nature, has generally been available. The two American Western artists, Frederic Remington and Charles M. Russell, are quite rare in autograph material, as is Albert Bierstadt.