In 1908, President Theodore Roosevelt crossed a river atop a moose.

via Reddit
This image is not real. It was made for a political Teddy Roosevelt used to campaign for the presidency in support of the Progressive Party, whose moose-themed mascot. Roosevelt faced off against the Democratic nominee Woodrow Wilson and the Republican incumbent William Howard Taft in this election. Roosevelt riding a horse was meticulously cropped out of a shot by Underwood and Underwood photography studio and placed over an image of a moose crossing a river. This picture was published in the New York Tribune on September 8, 1912.