The monument to the 2nd New York Cavalry Regiment is south of Gettysburg on Pleasonton Avenue. (39.808765° N, 77.234555° W; Google map; Tour map: Pleasonton Avenue) It was dedicated in 1892 by the State of New York.
The regiment was not on the field at Gettysburg, although it was active in cavalry duties throughout the Gettysburg Campaign. Pleasonton Avenue has several monuments to units like this.
From the front of the monument (top right):
2nd N.Y. Cavalry
From the tablet on rear of the monument:
This Regiment was engaged in the battles and skirmishes of the Cavalry Corps until the Brigade reached Hanover Junction, June 30, 1863, when it was moved hastily to Manchester, to guard trains against rumored movements of the enemy, and picketed the surrounding country. July 4th Joined 3rd Division in pursuit of the enemy and participated in the Cavalry engagements until the enemy retreated into Virginia.
See more on the 2nd New York Volunteer Cavalry Regiment in the Civil War