a sprinkler system was operated continually to keep the white oak structural timbers from warping and checking. On 3 September 1971, Cairo was listed on the National Register of Historic Places. In 1972, the U.S. Congress enacted legislation authorizing the National Park Service to accept the title to Cairo and restore the gunboat for display in Vicksburg National Military Park. Delays in funding the project halted progress until June 1977, when the vessel was transported to the park and partially reconstructed on a concrete foundation near the Vicksburg National Cemetery. A shelter to cover the vessel was completed in October 1980, with the museum opening in November. The original space-frame shelter has since been replaced by a tension-fabric system to provide better cover. The recovery of artifacts from Cairo revealed a treasure trove of weapons, ammunition, naval stores, and personal gear of the sailors who served on board. The gunboat and its artifacts can now be seen along the tour road at the USS Cairo Museum. These include a sailor's rope knife in good condition. Since salvage, Cairo has suffered degradation due to exposure to the elements, bird droppings, and vandalism. There are only four surviving Civil War-era ironclads in existence: , , USS Cairo, and CSS Muscogee. See also Anaconda Plan Mississippi Squadron Union Navy List of United States Navy ships Notes References This article includes information from the National Park Service and is in the public domain. External links USS Cairo Gunboat and Museum USS Cairo (DANFS photos) National Park Service site Drive On Documentary about James Eads building the City Class Ironclads Ships of the Union Navy Ships built in Mound City, Illinois Steamships of the United States Navy Gunboats of the United States Navy American Civil War patrol vessels of the United States 1861 ships Ships sunk by mines Shipwrecks of the Yazoo River Shipwrecks of the American Civil War Mississippi in the American Civil War Museum ships in Mississippi Museums in Warren County, Mississippi American Civil War museums in Mississippi Naval museums in the United States American Civil War on the National Register of Historic Places Ships preserved in museums Buildings and structures in Vicksburg, Mississippi Ironclad warships of the Union Navy Vicksburg National Military Park Historic American Engineering Record in Mississippi National Register of Historic Places in Warren County, Mississippi Shipwrecks on the National Register of Historic Places in Mississippi Maritime incidents in December