The Weeks Act is a federal law (36 Stat. 961) enacted by the United States Congress on March 1, 1911. Introduced by Massachusetts Congressman John W. Weeks and signed into law by President William Howard Taft, the law authorized the US Secretary of Agriculture to "Examine, locate and recommend for purchase ... such lands within the watersheds of navigable streams as ... may be necessary to the regulation of flow of navigable streams...." This meant that the federal government would be able to purchase private land if the purchase was deemed necessary to protect rivers' and watersheds' headwaters in the eastern United States. Furthermore, the law allowed for land acquired through this act to be preserved and maintained as national forest territory. Six years earlier, the Transfer Act of 1905 transferred control over the federal forest reserves from the General Land Office of the Department of the Interior to the Department of Agriculture and its Forest Service. Responsibility for land purchased through the Weeks Act was not given to former Chief Forester Gifford Pinchot because he resigned in 1907, with the stipulation that he would only resign if he could appoint his successor. This stipulation led to the Forest Service's tradition of picking a head with forestry knowledge. With the land acquired through the Weeks Act, Pinchot's successor obtained the power to issue permits for water power development on National Forests. The Weeks Act appropriated $9 million to purchase 6 million acres (24,000 km2) of land in the eastern United States.
The Weeks Act also provided measures for more cooperation between federal and state governments in regard to fire control. This legislation was heavily influenced by the fire season of 1910 because it wreaked havoc across the western United States, particularly in Idaho, where 85 people, including 72 firefighters, were killed in fires and more than 3 million acres (12,000 km2) of land and roughly 8,000,000,000 board feet (19,000,000 m3) of timber were destroyed by fires that year. This year's fire season alone put the US Forest Service $1.1 million in debt.