It runs in a north–south direction in south central Wisconsin from Brodhead to Brooklyn.

[1][2] WIS 104 was first designated in 1919–1920, running along its current route north of Broadhead before turning east then north to WIS 10 in Evansville.

[3][4] In 1923–1926, the highway was rerouted, removing all of its sections not on the current route and adding a short section to connect to WIS 59.

[5][6] Its route then remained unchanged until 1999 when it was extended 8.9 miles (14.3 km) north to its present northern terminus at WIS 92 in Brooklyn.

[1][7][8] The entire highway is along the Green county line.