The state seal in the center of the South Dakota state flag shows state activities when it joined the Union in 1889.  A farmer is using a horse-drawn plow to turn over a field.  A steamboat, which represents trade and transportation, glides along the Missouri River.  The state's Black Hills are shown in the distance. Buildings represent mining and manufacturing.  Cattle and corn represent the state's agriculture.  Rays of sun along with the name of the state and its nickname, the Mount Rushmore State, circle the seal.  The state motto is on a scroll in the seal.