economy. By 1900 several railroad lines branched from Cairo. In addition to shipping and railroads, a major industry in Cairo was the operation of ferries. Into the late 19th century, nearly 250,000 railroad cars could be ferried across the river in as little as six months. Vehicles were also ferried, as there were no automobile bridges in the area in the early 20th century. The ferry industry created numerous jobs in Cairo to handle large amounts of cargo and numerous passengers through the city. Wealthy merchants and shippers built numerous fine mansions in the 19th and early 20th century, including the Italianate Magnolia Manor, completed in 1872, and the Second Empire Riverlore Mansion, built by Capt. William P. Halliday in 1865. Across the street from the customs house, the Cairo Public Library was constructed in 1883 of Queen Anne-style architecture, finished with stained glass windows and ornate woodwork. The library was dedicated on July 19, 1884 as the A. B. Safford Memorial Library. Anna E. Safford paid for the construction of the Library and donated it to the city. These and other significant buildings are also listed on the National Register. For protection from seasonal flooding, Cairo is completely enclosed by a series of levees and flood walls, due to its low elevation between the rivers. Several buildings, including the old custom house, were originally designed to be built to a higher street level, to be at the same height as the top of the levees. That plan was scrapped as the cost of fill to raise the streets and surrounding land to that height proved to be impractical. In 1914 a large flood gate was constructed by Stupp Brothers of St. Louis, Missouri. The flood gate is known as the "Big Subway Gate", and it was designed to seal the northern levee in Cairo by closing over U.S. Highway 51. The gate weighs 80 tons, is 60 feet wide, 24 feet high, and five feet thick. With the addition of the gate, Cairo could become an island, completely sealed off from approaching flood waters. Following the Great Mississippi Flood of 1927, the levee system around Cairo was strengthened. As part of this project, the Corps of Engineers established the Birds Point-New Madrid Floodway. The Ohio River flood of 1937 brought a record water level to Cairo that crested at 59.5 feet. To protect Cairo, Corps of Engineers closed the