NY 17B begins at an intersection with
NY 97 in the
hamlet of
Callicoon. Known as Mill Street for the first block, NY 17B proceeds downhill and meets an intersection with the eastern end of
Sullivan County Route 133 (CR 133). After merging with CR 133, NY 17B proceeds east along the East Branch of Callicoon Creek and through the town of
Delaware. The mainly rural roadway winds east for several miles, reaching the southern end of the hamlet of
Hortonville. Passing the intersection with
CR 121, the route crosses through Hortonville before turning southeast, passing multiple industries in the area. Turning further south, NY 17B continues paralleling the East Branch, passing multiple farms before making several jaunts to the southeast. A short distance later, the route bends east and then northeast, reaching an intersection with
NY 52A. At this junction, NY 17B becomes county-maintained and designated
CR 117. NY 17B and CR 117 bend southeast again, reaching a junction with
NY 52 in the town of
Cochecton. NY 17B and NY 52 become concurrent, proceeding southward past multiple farms before reaching the hamlet of
Fosterdale. At this junction, NY 52 forks southward at an intersection with
CR 114 while NY 17B turns eastward. NY 17B passes south of Fosterdale Cemetery, passing rows of homes on the northern side of the roadway. The route passes along the southern end of Kazens Pond, crossing junctions with several local roads, including Hurd Road, which connects NY 17B to the
Bethel Woods Center for the Arts, the site of the
Woodstock Music Festival. Now in the town of
Bethel, NY 17B continues eastward, passing south of Lynch's Pond. The route crosses through the hamlet of Odell, passing north of Chestnut Ridge Pond and reaching the hamlet of Bethel. Passing several cemeteries east of Bethel, the route soon reaches the hamlet of
White Lake area, intersecting with
NY 55 and
CR 13. Running along the southern shore of White Lake, NY 17B and NY 55 proceed east into the hamlet of White Lake, passing numerous lakeside homes on the northern end of the highway. A short distance into White Lake, NY 55 forks north onto
CR 14 north towards
Swan Lake. NY 17B continues east out White Lake, returning to the rural areas of the town of Bethel. The route bypasses the hamlet of Smallwood, reaching an intersection with
CR 183 (Airport Road), which connects to
Sullivan County International Airport. NY 17B makes a short dart to the southeast before straightening east again and crossing over the
Mongaup River. After a short parallel with the Mongaup River, NY 17B continues east and soon northeast into the hamlet of Coopers Corners. A short distance outside of Coopers Corners, the route crosses into Maplewood, entering the town of
Thompson. The route intersects with
CR 59 (Kaufman Road) before reaching Valet Road, which is the access road to
Monticello Raceway. The route soon passes the stables for the raceway, passing West Broadway, which connects the route to downtown
Monticello. The route soon turns northeast again, crossing Jefferson Street and entering exit 104 of
NY 17, which marks the eastern end of NY 17B. The route continues northwest alongside NY 17 as
CR 174. ==History==