 Complete the following phrase:  In late September 1862, Altoona was home to the War Governors Conference which brought together 13 governors of Union states. This body gave early approval to the Emancipation Proclamation. The town grew rapidly in the late 19th century, its population approximately 2,000 in 1854, 10,000 in 1870, and 20,000 in 1880. The demand for locomotives during the Civil War stimulated much of this growth, and by the later years of the war, Altoona was known as a valuable city for the North. Altoona was also the site of the first Interstate Commission meeting to create and design the Gettysburg National Cemetery following the devastating 