New York State Route 840 (NY 840) is an east–west state highway in Oneida County, New York, in the United States. It is a superhighway extension of Judd Road (County Route 840 or CR 840), which ended at Halsey Road in Whitestown prior to the construction of NY 840. The western terminus of NY 840 is at the junction of Judd and Halsey Roads while the eastern terminus is at NY 5, NY 8, and NY 12 near the southern city line of Utica.

NY 840 first opened to traffic in 2005. It was ceremoniously designated as the Officer Joseph D. Corr Memorial Highway in 2007. In 2008, part of Judd Road was redesignated as CR 840 to match the designation of the state highway it connected to.

NY 840 begins at an intersection with Halsey Road and Judd Road in the town of Whitestown. North of this junction, NY 840 continues as Judd Road, designated as CR 840. NY 840 initially heads south as a four-lane undivided highway through a rural portion of Oneida County to a junction with Clark Mills Road, then turns southeast to parallel a set of high-voltage power lines through the town. Upon crossing into the town of New Hartford, NY 840 becomes a limited-access highway and turns to follow a more easterly routing.

As NY 840 approaches the residential outskirts of Utica, it connects to Middle Settlement Road by way of a Partial cloverleaf interchange. East of the junction, NY 840 curves southeastward and enters a major commercial district, where it intersects NY 5A by way of a single-point urban interchange. The district is confined mostly to the vicinity of NY 5A, however, and NY 840 proceeds southeast through residential neighborhoods and around pockets of commercial development to a cloverleaf interchange with the North–South Arterial (NY 5, NY 8, and NY 12) near the southern city line of Utica. NY 840 ends here; however, the highway continues southeast through the interchange as NY 8.

Although NY 840 is signed as an east–west route, the reference markers along NY 840 are sequenced from the arterial concurrency northward, ending at the Halsey Road intersection, in violation of standard New York State Department of Transportation (NYSDOT) practice. NYSDOT also lists the mileposts along the route from east to west in its annual Traffic Volume Report, implying a north–south orientation; however, NY 840 is listed as an east–west route in the NYSDOT route log, listing its "beginning" terminus at CR 40 (Judd Road, now CR 840).

The first section of NY 840 opened to traffic in June 2005. The entirety of the highway opened on October 3, 2005. In April 2007, a bill was introduced in the New York State Senate that would ceremoniously designate NY 840 as the "Officer Joseph D. Corr Memorial Highway". It was passed by both houses of the New York State Legislature and signed into law by Governor Eliot Spitzer on July 18, 2007.

NY 840 is commonly known as Judd Road Extension in reference to Judd Road, the county-maintained road it connects to at its western end. Judd Road and Coleman Mills Road, the continuation of Judd Road north of the former Oneida County Airport, were initially designated as CR 40. Meanwhile, Sutliff Road, a road branching off of Coleman Mills Road near the airport, was originally CR 90. In September 2008, legislation was introduced in Oneida County that would redesignate the portion of Judd and Coleman Mills Roads from Halsey Road to Sutliff Road and all of Sutliff Road as CR 840. The changes were proposed in an effort to bring the highways, which connect NY 840 to NY 233, under one designation that would serve as a clear continuation of NY 840 through northwest Whitestown. The redesignation was approved by the county legislature on September 24, 2008.

The entire route is in Oneida County. All exits are unnumbered.