The Pinchot–Ballinger controversy, also known as the "Ballinger Affair", was a dispute between U.S. Forest Service Chief Gifford Pinchot and U.S. Secretary of the Interior Richard A. Ballinger that contributed to the split of the Republican Party before the 1912 presidential election and helped to define the U.S. conservation movement in the early 20th century.
In March 1909, President William Howard Taft began his administration by replacing Theodore Roosevelt's Secretary of the Interior, James Rudolph Garfield, with Richard A. Ballinger, a former Mayor of Seattle who had served as Commissioner of the General Land Office (GLO) under Secretary Garfield. Ballinger's appointment was a disappointment to conservationists, who interpreted the replacement of Garfield as a break with Roosevelt administration policies on conservationism. Within weeks of taking office, Ballinger reversed some of Garfield's policies, restoring 3 million acres (12,000 km²) to private use.
By July 1909, Gifford Pinchot, who had been appointed by President William McKinley to head the USDA Division of Forestry in 1898, and who had run the U.S. Forest Service since it had taken over management of forest reserves from the General Land Office in 1905, became convinced that Ballinger intended to "stop the conservation movement". In August, speaking at the annual meeting of the National Irrigation Congress in Spokane, Washington, he accused Ballinger of siding with private trusts in his handling of water power issues. At the same time, he helped to arrange a meeting between President Taft and Louis Glavis, chief of the Portland, Oregon, Field Division of the GLO. Glavis met with the president at Taft's summer retreat in Beverly, Massachusetts, and presented him with a 50-page report accusing Ballinger of an improper interest in his handling of coal field claims in Alaska.