Duncan E. McKinlay was an American lawyer and politician who served three terms as a U.S. Representative from California from 1905 to 1911.

The 59th United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from March 4, 1905, to March 4, 1907, during the fifth and sixth years of Theodore Roosevelt's presidency. The apportionment of seats in the House of Representatives was based on the 1900 United States census. Both chambers had a Republican majority.