New York State Route 373

In 1823, a company was funded to establish a settlement and fishing wharf opposite the city of Burlington, Vermont on Lake Champlain in order to assist in the growth of iron factories and to supply dormant energy to the Essex County area. The newly founded company chose the name "Port Kent" and located the new hamlet on a site north of Trembleau Point. The original alignment of what is now NY 373 began as a wide road that was built to access Port Kent from the nearby village of Keeseville.[5]

NY 373 exists entirely within the boundaries of Adirondack Park, a protected area maintained by the State of New York. Adirondack Park was created in the 1880s after concerns arose about logging trees in the area. The logging was a substantial part of New York's economy, but protests were lodged by The New York Times and others against the clearing of entire mountains and wilderness areas of trees. Public opinion turned firmly against the loggers by the 1880s, and the park was created in 1885. It was the first State Forest Preserve in America. The park was further protected in 1894 when a clause was added to the New York Constitution which banned the selling of timber from state parks.[6][7][8]

NY 373 heading eastbound with Lake Champlain in view

On April 16, 1827, a team of three surveyors were commissioned to determine a routing for a new highway leading from Hopkinton, a town in northeastern St. Lawrence County, to Lake Champlain.[9] The task took 26 days, after which it was determined that the highway would meet Lake Champlain at Fort Kent.[10] An act authorizing the construction of the highway was passed by the New York State Legislature on April 18, 1829. A total of approximately $38,500[11] (equivalent to $924,361 in 2021)[12] was devoted to the project by the state of New York through the same act.[11]

The 75-mile (121 km) highway opened in 1833 as a toll road named the Port Kent and Hopkinton Turnpike.[9] The turnpike had only one toll gate, located near the center of the route. Two years later, the turnpike commissioners petitioned to the state of New York, asking for permission to replace the single gate with two gates at opposite ends of the turnpike that would collect half of the toll amount. The commissioners believed that the change in the toll gate locations would result in higher revenue, allowing them to continue maintaining the highway.[13] The change was approved;[14][15] however, the toll road was dissolved anyway three years later on March 30, 1838. At that time, maintenance of the Port Kent–Hopkinton highway was transferred to the towns through which it ran.[16]

The Theodore Roosevelt International Highway, a transcontinental auto trail extending from Portland, Oregon, to Portland, Maine, was established in 1919.[17] In eastern New York, the highway went through Keeseville, Ausable Chasm, and Fort Kent along what used to be the Port Kent and Hopkinton Turnpike before entering Vermont by way of the Burlington–Port Kent Ferry across Lake Champlain.[18]

The state of New York assumed maintenance of most of the Ausable Chasm–Port Kent roadway at some point after 1920.[19] In the 1930 renumbering of state highways in New York, the entirety of the highway from Ausable Chasm to the Port Kent ferry landing was designated as NY 373,[2] despite the fact that the small portion of the route east of Lake Street in Port Kent was not maintained by the state at the time.[20] On April 1, 1985, ownership and maintenance of NY 373 east of Lake Street was transferred from the town of Chesterfield to the state of New York as part of a highway maintenance swap between the state and Essex County.[21]