Union Pacific excursion to the 100th Meridian, 1866. Photograph by photography pioneer and Union Pacific's official photographer John Carbutt.

Caption on the back: "Photographed at Platte City Headquarters October 25, 1866. Seated is George Francis Train and behind him are Mrs. Train and T.C. Durant. Excursion to the 100th Meridian." When Casement and his crews passed this point, it guaranteed the Union Pacific the irrevocable right to continue westward, as stipulated in the Pacific Railroad Act. Thomas Durant, the vice president and general manager of Union Pacific, hosted a "100th Meridian Excursion" with a group of politicians, reporters, and other notable figures. Union Pacific photographer John Carbutt produced a series of stereographic cards titled Rail Road Excursion to the 100th Meridian. https://plattebasintimelapse.com/2015/05/excursion-to-the-100th-meridian/