river port for steamboats, which traveled all the way south to New Orleans. The city had been designated as a port of delivery by Act of Congress in 1854. A new city charter was written in 1857, and Cairo flourished as trade with Chicago to the north spurred development. By 1860, the population exceeded 2,000. During the Civil War, Admiral Andrew Hull Foote made Cairo the naval station for the Mississippi River Squadron on 6 September 1861. Since Cairo had no land available for base facilities, the navy yard repair shop machinery was afloat aboard wharf-boats, old steamers, tugs, flat-boats, and rafts. In January 1862, General Ulysses S. Grant occupied the city, and had Fort Defiance constructed to protect the confluence. Cairo became an important Union supply base and training center for the remainder of the war. Military occupation caused much of the city's trade to be diverted by railroad to Chicago. Cairo failed to regain this important trade after the war, as more railroads converged on Chicago and it developed at a rapid pace, attracting stockyards, meat processing, and heavy industries. Instead, agriculture, lumber, and sawmills now dominated the Cairo economy. Post-war prosperity The strategic importance of Cairo's geographic location during the Civil War sparked prosperity in the town. Several banks were founded during the war years, and the growth in banking and steamboat traffic continued after the war. In 1869 construction began on the United States Custom House and Post Office, which was designed by Alfred B. Mullet, the Supervising Architect. The custom house was completed in 1872. It served as a custom house, post office, and United States Court. The U.S. District Court for the Southern District of Illinois met at the building until 1905. From 1905 to 1942, the Custom House was used for the U.S. District Court for the Eastern District of Illinois. The building also housed the U.S. Circuit Court for the Eastern District of Illinois from 1905 to 1912. At the height of Cairo's prosperity, the post office in the building was the third busiest in the United States. It is one of only seven of Mullet's Victorian structures remaining in the nation, and the building has been converted for use as a museum. It is listed on the National Register of Historic Places. After the Civil War, the city became a hub for railroad shipping in the region, which added to its