New York City mayor John Francis Hylan's original plans for the Independent Subway System (IND), proposed in 1922, included building over of new lines and taking over nearly of existing lines, which would compete with the IRT and the Brooklyn–Manhattan Transit Corporation (BMT), the two major subway operators of the time. The IND Sixth Avenue Line was designed to replace the elevated IRT Sixth Avenue Line. The first portion of the line to be constructed was then known as the Houston–Essex Street Line, which ran under Houston, Essex, and Rutgers Streets. The contract for the line was awarded to Corson Construction in January 1929, and construction of this section officially started in May 1929.