Town guide · Somerset County
Living in Green Brook, NJ
Green Brook is a township of about four and a half square miles at the foot of the Watchung Mountains, with U.S. Route 22 running through it. At the top of the First Watchung Mountain is Washington Rock, where General Washington watched British troop movements in 1777.
- County
- Somerset
- Population
- About 7,300 (2020 census)
- Size
- About 4.4 square miles
- Setting
- Suburban township between the Route 22 corridor and the First Watchung Mountain
- Main roads
- U.S. Route 22 and County Routes 527 and 529
First things first
Green Brook, North Plainfield and a shared ZIP code
Green Brook was created in 1872 as North Plainfield Township. The Borough of North Plainfield split off in 1885 and the Borough of Watchung in 1926, and what remained was renamed Green Brook Township in 1932. Today North Plainfield, Watchung and Green Brook are three separate towns with separate governments and taxes.
Most of Green Brook also shares the 08812 ZIP code with Dunellen, a separate borough in Middlesex County. When we price or search for a home, we always confirm the actual municipality, because that decides the tax rate and the town services.
The lay of the land
Named for the brook
The township takes its name from the Green Brook, which rises in the Watchung Mountains and flows about 15 miles southwest to the Raritan River at Bound Brook. The brook is said to be named for the color of its water. Green Brook borders Bridgewater, North Plainfield, Warren and Watchung in Somerset County, Middlesex and Dunellen in Middlesex County, and Plainfield in Union County.
- Washington Rock: An old place name for the area around the overlook at the top of the First Watchung Mountain.
- Seeley Mills: Another historic place name that still appears in the township.
- The Route 22 corridor: U.S. Route 22 is the main highway through town.
Homes
What you will find
- Single family homes: Detached houses make up most of the township, on streets between Route 22 and the First Watchung Mountain.
- Homes near the brooks: Properties in lower areas near the Green Brook, where flood maps deserve a close look.
Worth knowing: The Green Brook has a long flood history along its course, including major floods in 1971 and 1973 and damage from Hurricane Floyd in 1999, and the township has its own Green Brook Flood Control board. We check the flood zone map on every home in the lower parts of town, and we confirm the sewer situation early, because both affect inspections, insurance and buyer questions.
Property taxes
What taxes look like in Green Brook
- 2.165%2025 effective tax rate, as a share of market value
- $14,8212025 average residential tax bill
A home worth $700,000 on today's market would pay roughly $15,155 a year at Green Brook's 2025 effective rate. Your actual bill depends on your assessment, so we pull the real tax record for any home you are considering.
Source: New Jersey Division of Taxation, 2025 general and effective tax rates. Rates are set each year.
Getting around
Roads and commuting
U.S. Route 22 is the main highway through Green Brook, and County Routes 527 and 529 also pass through the township. There is no train station in Green Brook. The closest is next door at Dunellen, on NJ Transit's Raritan Valley Line. NJ Transit buses stop along Route 22, and local route 822 serves the township. Newark Liberty International Airport is about 23 miles away.
Places worth knowing
Parks, landmarks and open space
- Washington Rock State Park: A state park of about 34 acres inside the township, atop the First Watchung Mountain, set aside in 1913 to mark where Washington watched British troop movements in 1777, with picnic areas and long views east.
- Arthur Lewis Park: A township park at 59 Greenbrook Road with a fenced spray park whose water features run on a hand activated cycle in summer.
- Watchung Reservation: Just outside the township to the east in Union County, a reservation of about 2,000 acres with trails, ponds and the old village of Feltville.
Common questions
Questions people ask us about Green Brook
What are property taxes in Green Brook, NJ?
Green Brook Township's 2025 effective tax rate is 2.165 percent of market value, and the average residential tax bill is $14,821, according to the New Jersey Division of Taxation. Actual bills depend on each home's assessment.
Is Green Brook part of North Plainfield?
No. Green Brook was called North Plainfield Township until 1932, but it is a separate municipality from the Borough of North Plainfield, with its own government and property taxes.
Is there a train station in Green Brook?
No. The closest station is in neighboring Dunellen, on NJ Transit's Raritan Valley Line. NJ Transit buses also stop along Route 22.
Why do Green Brook and Dunellen share a ZIP code?
Most of Green Brook uses the 08812 ZIP code, which it shares with Dunellen in Middlesex County. ZIP codes follow postal routes, not town lines, so we always confirm the municipality on every home.
What is Washington Rock?
Washington Rock is a rock outcropping and overlook on the First Watchung Mountain in Green Brook. General Washington used it in 1777 to watch British troops under General William Howe, and the land was bought in 1913 to create a park marking those events.
Nearby towns
Towns that border Green Brook
Buying or selling in Green Brook?
From the mountain down to the brook
A house up near Washington Rock and one in the low ground by the Green Brook raise different questions. We check the flood map and the 08812 address on every home, then go over your options with you.
Call or text either of us directly.