The LIE was built over much of Horace Harding Boulevard within Eastern Queens and Power House Road within western Nassau County. Prior to the LIE's construction, the route was designated as NY 25D. In May 1951, the New York City Board of Estimate approved the widening of Horace Harding Boulevard and Power House Road to 260 feet, and constructing an expressway in the road's median at a cost of $25 million. The New York State Department of Public Works later modified the highway's route in the vicinity of Little Neck Parkway, near the Queens-Nassau border. At Little Neck Parkway, Horace Harding Boulevard continues northeast and then eastward, whereas the LIE takes a more southerly path. This modification was enacted because of complaints from nearby residents. In 1955, New York State Governor Thomas E. Dewey approved plans for a extension of the LIE between the Queens-Nassau border and Riverhead in Suffolk County.