Mountainside Boro is in Union County, New Jersey. Its tax roll lists 139 blocks and 2,858 lots.
139 blocks · Union County
The median assessed value in Mountainside Boro is $587,000. 75 sales were recorded in the last 12 months, not counting nominal transfers, at a median price of $999,000. The most recent sale on record was 209 Central Avenue, Mountainside, NJ 07092, for $1,215,000 on Sep 22, 2026. 5 foreclosure cases are open.