Western Terminus: Main Street and Bay Avenue at the Patchogue village line
Eastern Terminus: Montauk Highway (NY 27A) and Knoll Road in Shinnecock Hills
Distance: 32.50 miles
Montauk Highway in the southernmost major east/west route in Suffolk County. It is also the longest named road on Long Island, running almost the entire length of Suffolk from Copiague to Montauk. The entire length of Montauk Highway used to be a state road, designated as NY 27A from Copiague to Southampton and NY 27 from Southampton to Montauk. In 1972, the portion of NY 27A east of Oakdale, where it has an interchange with Sunrise Highway (NY 27), was decommissioned. Currently, this section is designated CR 85 from Oakdale to Patchogue and CR 80 from Patchogue to Shinnecock. The two routes are connected by a short, unnumbered local street called Main Street in Patchogue. CR 80 begins at the Patchogue village line and runs east until Knoll Road, where Montauk Highway comes under state jurisdiction with an unsigned designation of NY 27A and a reference route number of 900W. It is a two-lane undivided road in most places. CR 80 is the longest county route in Suffolk.