From the Summary: "Congress enacted the Wilderness Act in 1964. This act created the National Wilderness Preservation System, reserved to Congress the authority to designate wilderness areas, and directed the Secretaries of Agriculture and of the Interior to review certain lands for their wilderness potential. The act also designated 54 wilderness areas with 9 million acres of federal land. Congress began expanding the Wilderness System in 1968, and as of July 15, 2019, there are 803 wilderness areas, totaling over 111 million acres, in 44 states and Puerto Rico. Numerous bills to designate additional areas and to expand existing ones have been introduced and considered in every Congress."
CRS Report for Congress, RL31447
Congressional Research Service: https://crsreports.congress.gov/