Garwood was incorporated as a borough on March 19, 1903, from portions of Cranford Township and Westfield Town.
In the north side of Garwood, most of the streets are numbered, while in the south side of Garwood most of the streets are named after trees.
As of the census of 2000, there were 4,153 people, 1,731 households, and 1,125 families residing in the borough. The population density was 6,292.9 people per square mile (2,429.5/km²). There were 1,782 housing units at an average density of 2,700.2/sq mi (1,042.5/km²). The racial makeup of the borough was 95.91% White, 0.36% African American, 1.32% Asian, 1.54% from other races, and 0.87% from two or more races. Hispanic or Latino of any race were 4.98% of the population.
There were 1,731 households out of which 26.2% had children under the age of 18 living with them, 49.0% were married couples living together, 12.1% had a female householder with no husband present, and 35.0% were non-families. 28.7% of all households were made up of individuals and 11.5% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.96.
In the borough the population was spread out with 20.0% under the age of 18, 6.3% from 18 to 24, 35.6% from 25 to 44, 20.9% from 45 to 64, and 17.2% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 93.3 males. For every 100 females age 18 and over, there were 89.6 males.
The median income for a household in the borough was $52,571, and the median income for a family was $64,053. Males had a median income of $50,951 versus $36,538 for females. The per capita income for the borough was $26,944. About 3.5% of families and 5.1% of the population were below the poverty line, including 6.3% of those under age 18 and 6.4% of those age 65 or over.
The Garwood station offers limited New Jersey Transit rail service on the Raritan Valley Line. The station has limited service on weekdays only. The Garwood Station does not have platforms and is not ADA compliant.
New Jersey Transit also provides bus service along two different lines, the 113 route to the Port Authority Bus Terminal in Midtown Manhattan, and the 59 bus to Newark.
Newark Liberty International Airport is approximately 15 minutes away and Linden Airport, a general aviation facility is in nearby Linden, New Jersey.