The IRT Ninth Avenue Line, often called the Ninth Avenue Elevated or Ninth Avenue El, was the first elevated railway in New York City. It opened on July 3, 1868 as the West Side and Yonkers Patent Railway, as an experimental single-track cable-powered elevated railway from Battery Place, at the south end of Manhattan Island, northward up Greenwich Street to Cortlandt Street. It ceased operation on June 11, 1940, after it was replaced by the IND Eighth Avenue Line which had opened in 1932. The last section in use, over the Harlem River, was known as the Polo Grounds Shuttle, and closed on August 31, 1958. This portion used a now-removed swing bridge called the Putnam Bridge, and went through a still-extant tunnel with two partially underground stations. History West Side and Yonkers Patent Railway On April 20, 1866, the West Side and Yonkers Patent Railway Company was formed by Charles T. Harvey and eventually was awarded the approval to begin construction of an elevated line operating on Greenwich Street, then Ninth Avenue from Battery Place to 30th Street. His company had been chartered with a subscribed capital of $100,000, to build a elevated railroad from the southern extremity of the city northward its length and thence to the village of Yonkers. Construction on the line began on July 1, 1867. The first column was erected on October 7, 1867 and was tested in December 1867. The line was dubbed the "one-legged railroad," because the single track ran above the street on a single row of columns. The cable was a loop, driven by a stationary engine, that ran between the rails for propulsion of the cars, and then returned under the street. The equipment included three complete passenger cars; four vaults where the machinery was located; and patent rights. The line opened for business on July 3, 1868 The State Commissioners who authorized the "experiment" declared it a success, and the Governor authorized its completion to Spuyten Duyvil. The name was later changed to the West Side and Yonkers Patent Elevated Railway Company. The original northern terminus was 29th Street, and the southern terminus was Dey Street. The line used multiple -long cable loops, driven by steam engines in cellars of buildings adjacent to the track. Each loop was started when a car neared it and stopped when it had passed. The cables were equipped with collars fastened firmly