The Hudson River School was an American art movement of the mid-19th century, characterized by its romantic and idealized landscapes. The term SHADS is an acronym for the four main painters of the school: Thomas Cole, Asher Durand, Frederic Edwin Church, and John Frederick Kensett. These four artists were the most influential of the Hudson River School, and their works are considered to be some of the most important American paintings of the 19th century.