Having reached the floor of the Hudson Valley, NY 23 assumes a southeast-trending route through the town of Cairo. It comes close to the hamlet of Cairo, but bypasses it on a four-lane divided highway that takes it around the northern fringe of the community. As it runs around Cairo, the route connects to NY 145 and briefly overlaps NY 32, the major north–south state route on the west side of the Hudson River. NY 23 continues as a divided highway through mostly forested areas to the town of Catskill, where it crosses Catskill Creek and has an indirect intersection with the New York State Thruway (I-87). Not far to the southeast is the village of Catskill, the county seat of Greene County. NY 23 bypasses this community as well, connecting to U.S. Route 9W (US 9W) and NY 385 at junctions in lightly populated areas north of the village prior to crossing the Hudson River on the Rip Van Winkle Bridge.