 The Exchange merged back together after the war.The $2 million venue measured by and was actually two separate buildings.The second and third floors of the western half of the building had an iron truss system that supported the roof and created the largest open indoor space in the United States at the time of its construction (235 feet long and wide and tall) and thus was chosen for the 1876 convention which was the first Democratic or Republican national convention west of the Mississippi River.