Plainfield is a city in Union County, New Jersey, United States, known by its nickname as “The Queen City.” As of the 2010 United States Census, the city’s population increased to 49,808, its highest ever recorded population in any decennial census, with the population having increased by 1,979 (+4.1%) from the 47,829 counted in the 2000 Census, which had in turn increased by 1,262 (+2.7%) from the 46,567 counted in the 1990 Census.

The area of present-day Plainfield was originally formed as Plainfield Township, a township that was created on April 5, 1847, from portions of Westfield Township, while the area was still part of Essex County. On March 19, 1857, Plainfield Township became part of the newly created Union County.

Plainfield was incorporated as a city by an act of the New Jersey Legislature on April 21, 1869, from portions of Plainfield Township, based on the results of a referendum held that same day. The city and township coexisted until March 6, 1878, when Plainfield Township was dissolved and parts were absorbed by Plainfield city, with the remainder becoming Fanwood Township (now known as Scotch Plains).

Unincorporated communities, localities and place names located partially or completely within the city include Netherwood.

The city is located in Central Jersey on the southwestern edge of Union County and is bordered by nine municipalities. Scotch Plains lies to the north and east, and Fanwood to the northeast. Bordered to the south are South Plainfield, and Piscataway. To the southwest lies Dunellen and to the southeast, Edison. All which are in Middlesex County. Green Brook Township lies to the northwest, North Plainfield lies to the north and Watchung borders to the northwest. All three of these municipalities are in Somerset County.

As of the 2010 United States Census, there were 49,808 people, 15,180 households, and 10,884 families residing in the city. The population density was 8,270.1 per square mile (3,193.1/km²). There were 16,621 housing units at an average density of 2,759.8 per square mile (1,065.6/km²). The racial makeup of the city was 23.54% (11,724) White, 50.20% (25,006) Black or African American, 0.91% (455) Native American, 0.95% (474) Asian, 0.05% (26) Pacific Islander, 20.13% (10,024) from other races, and 4.21% (2,099) from two or more races. Hispanic or Latino of any race were 40.37% (20,105) of the population.

Portions of Plainfield are part of an Urban Enterprise Zone. In addition to other benefits to encourage employment within the Zone, shoppers can take advantage of a reduced 3½% sales tax rate (versus the 7% rate charged statewide) at eligible merchants.

Source: Wikipedia