- Southern Terminus:
- Division Street (CR 65) in Patchogue
- Northern Terminus:
- Portion Road (CR 16) in Lake Ronkonkoma
- 6.72 miles
CR 19 is a north/south route from Patchogue to Lake Ronkonkoma. The first section is a two-lane divided road called West Avenue that begins at the eastern terminus of CR 65 and runs north through a townhouse development, crosses Main Street just east of the eastern terminus of CR 85, and then curves to the west to merge into Lake Street, which runs along the south side of Patchogue Lake. After one block, Lake Street ends at a traffic circle. CR 19 turns north onto Waverly Avenue. After about half a mile, Waverly Avenue has an interchange with Sunrise Highway (NY 27), where widens to become a four-lane divided highway and curves to the northeast. After a short distance, it changes names to become Patchogue-Holbrook Road. It runs on a diagonal to Holbrook, where it has an interchange with the Long Island Expressway (I-495). North of the expressway, it curves to the west and then to the north. After about half a mile, it ends at Portion Road (CR 16) in Lake Ronkonkoma.