New York State Route 43

New York State Route 43 (NY 43) is a state highway in Rensselaer County, New York, in the United States. It extends for 24.00 miles (38.62 km) from Interstate 90 (I-90) exit 8 in North Greenbush to the Massachusetts state line, where it continues into Williamstown as Massachusetts Route 43. Most of NY 43 is a two-lane highway that passes through a mixture of rural and residential areas; however, its westernmost 2 miles (3.2 km) between I-90 and U.S. Route 4 (US 4) is a four-lane divided highway. NY 43 has an overlap with NY 66 in Sand Lake and intersects NY 22 in Stephentown.

When NY 43 was first assigned in the 1920s, it began near the village of Schoharie and ended in downtown Albany. Initially, the portion of modern NY 43 east of Averill Park was designated as part of New York State Route 7 in 1924. It was renumbered to New York State Route 45 by 1926 and became part of an extended NY 43 as part of the 1930 renumbering of state highways in New York. NY 43 was originally routed on Broadway and Washington Avenue in Rensselaer; however, it was rerouted to use 3rd Avenue and US 4 instead in the late 1960s.

In the early 1970s, the route was truncated to consist only of the portion east of the Hudson River. NY 43's former routing west to Schoharie was redesignated NY 443 as a result. NY 43 was realigned slightly in the late 1990s to serve the new exit 8 on I-90. Its former routing into Rensselaer on 3rd Avenue is now partly NY 151 and unsigned NY 915E.