County highway
County Route 18 was a county highway along Broadway Avenue from east of Sayville to Holbrook. It was an unsigned two-lane arterial spanning from Montauk Highway (CR 85) to CR 19 (Patchogue–Holbrook Road). A former segment of Broadway Avenue called "Old Broadway Avenue" runs east of the segment between Montauk Highway and somewhere south of Sunrise Highway along the border of Sans Soucci Lakes County Park and near a former Girl Scouts of the USA camp. The route was added to the Suffolk County highway system on January 27, 1930.