What is now Flemington was originally formed as a town by an Act of the New Jersey Legislature on March 14, 1870, within portions of Raritan Township. It became a village as of June 11, 1894, still within Raritan Township. Flemington was finally incorporated as an independent borough by an Act of the New Jersey Legislature on April 7, 1910, based on the results of a referendum held on April 26, 1910, and was formally separated from Raritan Township. The borough's incorporation was confirmed on April 27, 1931.
Flemington is an independent municipality located entirely within (and completely surrounded by) Raritan Township and is located near the geographic center of the Township. In 1756, Samuel Fleming purchased part of this land, and built his home which still stands on Bonnell Street, and "Fleming's Town" was born.
According to the United States Census Bureau, the borough has a total area of 1.1 square miles (2.8 km²), all of it land.
There were 1,804 households out of which 26.8% had children under the age of 18 living with them, 38.7% were married couples living together, 11.7% had a female householder with no husband present, and 44.7% were non-families. 37.7% of all households were made up of individuals and 12.1% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 3.00.
In the borough the population was spread out with 22.2% under the age of 18, 8.6% from 18 to 24, 36.9% from 25 to 44, 20.2% from 45 to 64, and 12.1% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 94.3 males. For every 100 females age 18 and over, there were 92.7 males.
The median income for a household in the borough was $39,886, and the median income for a family was $51,582. Males had a median income of $38,594 versus $31,250 for females. The per capita income for the borough was $23,769. About 5.0% of families and 6.9% of the population were below the poverty line, including 7.5% of those under age 18 and 3.0% of those age 65 or over.
Flemington Circle is the largest of three traffic circles in the environs of Flemington and sits just to the southeast of Flemington's historic downtown. U.S. Route 202 and Route 31 approach the circle separately from the north and continue south concurrent, and the circle is the eastern terminus of Route 12. It is one of only a handful of New Jersey's once-widespread traffic circles still extant according to its original design. The circle sees significant congestion on weekends because of the new developments and big-box retailers. Unlike most circles, traffic on US 202 does not yield on entry; US 202, being a main four-lane divided highway, gets the right-of-way.
Two other traffic circles exist on Route 12 just west of the Flemington Circle. Both handle a much smaller volume of traffic; the first one, at South Main Street, named the Main Street Circle (old Route 31), is also in Flemington, and the other, at Flemington Road / Route 523 (old Route 12) and Mine Street, is in Raritan Township. This circle is known informally amongst residents as Dvoor's Circle after the farm that surrounded parts of it. Route 12 traffic has the right of way in both of these circles, just as US 202 does in Flemington Circle.
The Mayor of Flemington Borough is Robert B. Hauck. Members of the Flemington Borough Council are Sandra Borucki, Erica Edwards, John Gorman, Linda Mastellone, Brooke Liebowitz and Mark Legato. Ms. Liebowitz and Mr. Legato were elected by the people of Flemington in the November 2006 elections. In the November 2007 election, Erica Edwards won a one-year seat; newcomer Linda Mastellone won a three-year seat, and John Gorman was re-elected to a three-year seat. The Borough Clerk is Diane Schottman, the Deputy Clerk is Anne Henning, the Chief Financial Officer is Bill Hance, Borough Attorney is Barry Goodman and the Police Chief is George Becker.
Public school students in grade 9 - 12 attend Hunterdon Central Regional High School, part of the Hunterdon Central Regional High School District, which serves over 3,000 students in central Hunterdon County. Students from Delaware Township, East Amwell Township, Flemington Borough, Raritan Township and Readington Township attend Hunterdon Central Regional High School.
The land that comprises Flemington was originally the territory of the Lenni Lenape Native Americans, as was all of Hunterdon County. In 1712, as part of a land parcel of 9,170 acres (37 km²), the Flemington area was acquired by William Penn and Daniel Coxe.
The surrounding fertile farmland dictated that the beginnings of Flemington should be essentially agricultural. Early German and English settlers engaged in industries dependent on farm products. As time passed poultry and dairy farms superseded crops in agricultural importance. An example of early settlement families was Johann David and Anna Maria Ephland, who immigrated in 1709 from Germany through London to New York and settled on his farm in 1710. They raised their seven children, and two from his previous marriage, on the farm that now makes up the core of Flemington.
In 1785, Flemington was chosen as the County Seat of Hunterdon. Fire destroyed the old courthouse in 1826 and the City of Lambertville made an attempt to have the Seat moved, to no avail. Flemington remained the County Seat and the Courthouse which stands today on Main Street was built.
In 1856, the Hunterdon County Agricultural society purchased 40 acres (16 ha) of land that would accommodate the people, exhibits and livestock for the County (Flemington) Fair. The purpose of this Fair was to promote competition between farmers, stock raisers and machinery manufacturers. The fair was held every year at the Flemington Fairgrounds which also was the site of Flemington Fair Speedway (later Flemington Raceway). From 1992 through 1995, the speedway hosted the Race of Champions, a prestigious race for Modified racers. The speedway hosted a NASCAR Craftsman Truck Series race from 1995 to 1998. In 2003, the County Fair adopted a new name, The Hunterdon County 4H and Agricultural Fair, and moved to the South County Park in East Amwell Township.
On February 13, 1935, a jury in Flemington found Bruno Richard Hauptmann guilty of the kidnapping and murder of Charles Lindbergh's baby boy.
By 1980, 65% of Flemington borough had been included on the New Jersey State Register of Historic Places and is now on the National Register of Historic Places.