While The Eight is often used as a synonym for the Ashcan School, this is really not the case. Robert Henri, an instructor at the Pennsylvania Academy of the Fine Arts, was the leader of the group formed in 1907 which included his students: Everett Shinn, John Sloan, George Luks, and William J. Glackens, who worked as newspaper illustrators in Philadelphia. Arthur B. Davies, Ernest Lawson, and Maurice Prendergast joined them for just one show together in 1908 at the MacBeth Gallery in NYC organized by Davies. They were dissatisfied with the status quo and were determination to bring Art into closer touch with everyday life. Some also showed in the infamous Armory Show of 1913, which Davies also had an important hand in.

Everett Shinn, Robert Henri and John Sloan

From the display at the New Britain Museum of American Art:

An Imaginative Boy by Robert Henri, 1915

Main Street, Gloucester by John Sloan, 1917
Spring Tapestry by Ernest Lawson, ca 1930
Pals by George Luks. ca 1907
Washington Square, Winter by William Glackens, 1930
French Vaudeville by Everett Shinn, 1937
These were online:

Evensong by Arthur Davies, ca 1898
Central Park, New York by Maurice Prendergast, 1901

The group actually disbanded, but continued their influence on what is known as the Ashcan School. Not a formal school, per se, the disciples continued the practice of illustrating contemporary American, often urban and poor, scenes. They rejected the refined themes of mythology and literature that were no longer pertinent in the Industrial Age. This group included artists such as: George Bellows, Reginald Marsh, Rockwell Kent, Alfred Maurer, Jacob Ris, and Edward Hopper.

Ashcan School in John Sloan's studio
Strokey's Bar by Reginald Marsh, 1940
The Big Dory by George Bellows, 1913
Toilers of the Sea by Rockwell Kent, 1907
 
 From the Barbara Belgrade Spargo Collection:

Flying Acrobats by Reginald Marsh, 1940
Head of Jean by William Glackens, 1918
Aspens by Ernest Lawson, 1928
 Girl Undressing (Stockings) by John Sloan, 1927
Portrait of a Young Girl by William Glackens, ca 1915
 Le Baou by William Glackens, 1925