bridge building, including the first railroad bridge across the Mississippi (now gone), an unusual two-track railroad bridge, and the largest roller dam in the world. The first railroad bridge across the Mississippi River was built between Arsenal Island and Davenport in 1856. Many steamboat pilots felt that the bridge had been intentionally positioned to make it hard for them to navigate, and this conflict reflected a larger rivalry: St. Louis and its steamboats against Chicago and its railroads. Two weeks after the bridge opened, the steamboat Effie Afton collided with the bridge, caught fire, and damaged the bridge. The owner of the Effie Afton sued the bridge company for damages, and Abraham Lincoln was one of the lawyers who defended the railroad. This test case was appealed to the United States Supreme Court, which ruled in favor of the railroad in 1872. Although the original bridge is long gone, a monument exists on Arsenal Island marking the Illinois side. On the Iowa side, the bridge was located near where 4th and Federal streets intersect with River Drive. The Lock and Dam No. 15 and the Government Bridge are located just southwest of the site of the first bridge. The Government Bridge, completed in 1896, is notable for having two sets of railroad tracks above the car lanes. There are only two bridges in the world with this feature. Three other bridges span the river between Rock Island and Davenport. The Crescent Rail Bridge is a railroad-only bridge, completed in 1899. The Centennial Bridge was completed in 1940 for autos only. The newest bridge is the Interstate 280 bridge, completed in 1973. Lock and Dam No. 15, completed in 1934 as a federal Works Progress Administration (WPA) project during the Great Depression, is the largest roller dam in the world. The dam is designed for navigation, not flood control. During flood season, the rollers are raised, unleashing the full flow of the water. On the south side of the city, overlooked by the Black Hawk State Historic Site, are auto and railroad crossings of the Rock River to Milan, Illinois. This set of bridges also crosses the historic Hennepin Canal and Sears Dam (this was named after the entrepreneur David B. Sears, who previously built the Sears Dam between Arsenal Island and Moline.) In 2007 a new bridge was completed between 3rd Street Moline/southeast Rock Island and Milan. It expedites the