Mexican muralism was the promotion of mural painting starting in the 1920s, generally with social and political messages as part of efforts to reunify the country under the post Mexican Revolution government. It was headed by “the big three” painters, Diego Rivera, José Clemente Orozco and David Alfaro Siqueiros. From the 1920s to about 1970s a large number of murals with nationalistic, social and political messages were created on public buildings, starting a tradition which continues to this day in Mexico and has had impact in other parts of the Americas, including the United States where it served as inspiration for the Chicano art movement.