The borough sits beside one of Union County’s largest natural areas, with Trailside Nature & Science Center, hiking, playgrounds and the Watchung Riding Stable serving as major visitor draws.
Union County · Watchung Reservation · Route 22
Mountainside, New Jersey
Mountainside is a compact Union County borough where quiet residential neighborhoods meet major outdoor destinations, a long Route 22 business corridor and convenient access to Westfield, Summit, Springfield and Berkeley Heights.
Use this NJTGO guide for borough services, schools, parks, history and recreation, plus direct access to deeper local business, dining, real estate, visitor, classified and jobs pages.
Union CountyCounty location
07092Mountainside ZIP code
1895Borough incorporation
Route 22Primary commercial corridor
About Mountainside
Mountainside was incorporated as a borough on September 25, 1895, from portions of Westfield Township. Today its identity is strongly shaped by wooded residential streets, Route 22 commerce and immediate access to major Union County parkland.
Echo Lake Park supports walking, fishing, seasonal recreation, playgrounds, ball fields, the September 11 Memorial and other county-park amenities.
Mountainside remains primarily residential, with public schools serving younger grades locally and high-school students attending Governor Livingston High School in Berkeley Heights.
Route 22 provides direct east-west access, while nearby Summit and Westfield stations provide NJ TRANSIT rail options for residents and visitors.
Government & Civic Resources
1385 U.S. Highway 22 East
Mountainside, NJ 07092
908-232-2400
Emergency: 911
Non-emergency: 908-232-8100
Municipal public works and local services
908-232-2409
1 Constitution Plaza
Mountainside, NJ 07092
908-233-0115
Schools & Education
Pre-K through Grade 2
1497 Woodacres Drive
Mountainside, NJ 07092
908-301-9104
Grades 3-8
302 Central Avenue
Mountainside, NJ 07092
908-232-8828
Mountainside students in Grades 9-12 attend Governor Livingston in Berkeley Heights.
175 Watchung Boulevard
908-464-3100
District resources include registration, calendars, transportation, board information and employment information.
Parks, Nature & Recreation
A 139-acre Union County park with lake recreation, fishing, picnic areas, playgrounds, athletic fields, dog-run access and the Union County September 11 Memorial.
A large Union County reservation with wooded trails, family recreation and access to major nature attractions in and around Mountainside.
452 New Providence Road
Environmental exhibits, educational programming and a key gateway to the Watchung Reservation trail system.
1160 Summit Lane
County-operated equestrian facility serving recreational riders and programs.
1005 Mountain Avenue
Seasonal community recreation and aquatic programs.
Approximately 0.9 mile of accessible fitness stations and park paths along the Echo Lake area.
History & Local Heritage
The historic house at Constitution Plaza is a central part of Mountainside’s local-history story and community preservation efforts.
Borough historyMountainside’s municipal history reaches back to its 1895 incorporation and earlier settlement patterns connected to the Watchung landscape and neighboring Westfield.
Community, Worship & Local Life
1449 Deer Path
Mountainside, NJ 07092
300 Central Avenue
Mountainside, NJ 07092
Municipal recreation programs use the pool, Deerfield facilities, courts and fields throughout the borough.
AMC Mountainside 10 and local studios add indoor entertainment, while the library and county park system support community programming.
Surrounding Communities
Mountainside is closely connected with Westfield, Springfield, Summit, Berkeley Heights and Scotch Plains. NJTGO keeps business and dining listings on the Mountainside pages limited to Mountainside addresses; nearby options appear only when a page clearly labels them as outside the borough.
Explore more of Mountainside
Use the dedicated town pages for deeper local businesses, restaurants, real estate, visitor information, community classifieds and employment resources.
Business & ShoppingFood & DrinkVisiting & LodgingCurrent-information review completed September 2026 using Borough of Mountainside, Mountainside School District, Union County, public institutional sources and current local-location data. Public contacts, hours and programs can change.