Toward the beginning of the Washington-Franklin era, in 1909, the Post Office issued its first individual commemorative stamps—three single 2¢ issues honoring, respectively, the Lincoln Centennial, the Alaska-Yukon Exposition, and the tercentennial/centennial Hudson-Fulton Celebration in New York. A four-stamp series commemorating the Panama–Pacific International Exposition in San Francisco, California appeared in 1913, but no further commemoratives were issued until after World War I. The Lincoln Centennial's portrait format distinguished it from all other commemoratives released between 1893 and 1926, which were produced exclusively in landscape format. (The next U. S. commemorative in portrait orientation would be the Vermont Sesquicentennial issue of 1927, and many have appeared since.)