Wheeling, once part of Virginia, became central to the creation of West Virginia during the Civil War. West Virginia Independence Hall, originally the Wheeling Custom House, also served as a post office and courthouse, and was the site of heated debates and two constitutional conventions that led to West Virginia's statehood in 1863. Built in 1859, the building is also historically significant for its internal skeletal structure of wrought iron I beams, box girders, and cast iron columns, an early use of a technique later used in skyscrapers. After Virginia voted to secede from the Union in April 1861, delegates from 27 northwestern Virginia counties met there on May 13, 1861, in the First Wheeling Convention to discuss forming a new state. The convention concluded that the differences between eastern and western Virginia were irreconcilable, adopted the Declaration of the Rights of the People of Virginia, and elected Francis H. Pierpont as Governor of the Restored Government of Virginia, making Wheeling Virginia's capital and this building the center of the new government. Although President Lincoln's cabinet was divided over creating a new state from Virginia, Lincoln signed the bill establishing West Virginia on December 31, 1862, and it entered the Union as the 35th state on June 20, 1863.