In 1928, the government of Carlos Ibáñez del Campo decided to reorganize the provinces of Chile, by Decree with Law Force N.° 8.582 dated 28 January 1929. The new province of Colchagua incorporated the departments of Rancagua (cap. Rancagua) and Cachapoal (cap. Peumo), originally from the province of O'Higgins, and the department of Santa Cruz (cap. Santa Cruz), which belonged to the province of Curicó.