Mountainside Flag

Mountainside

County:
Union County
County Seat:
No
Area (mi²):
3.996
State:
New Jersey

Mountainside is a borough located in Union County, New Jersey. Mountainside has a 2026 population of 7,228. Mountainside is currently growing at a rate of 2.69% annually and its population has increased by 3.38% since the most recent census, which recorded a population of 6,992 in 2020.

7.2K
Total Population
1,809
Density (mi²)
189 2.69%
Growth

Nearby Cities

Sources

  1. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  2. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  3. American Community Survey (2009 - 2013)
  4. Census QuickFacts
  5. Historical Populations of States and Counties (1790 - 1990)