Fullerton is a census-designated place (CDP) in Whitehall Township, Lehigh County, Pennsylvania, in the United States. Fullerton is a suburb of Allentown, in the Lehigh Valley region of the state.The population of Fullerton was 14,925 at the 2010 census.HistoryOriginally known as Ferndale, the town was located on tracts of land originally settled by Giles Windsor, Stephen Snyder and Jacob Yundt . In 1895, the town was renamed "Fullerton" in honor of local businessman James W. Fuller Jr., who had purchased the railroad car wheel factory of Frederick & Company in 1865 and operated it as McKee, Fuller & Co. and later the Lehigh Car, Wheel & Axle Works. Fuller laid out the hamlet in 1870, and by 1883 it was a thriving company-town with a population in excess of 1,500 men and their families. When the Lehigh Valley cement industry exploded in the early 1900s, Fuller's company prospered by providing machinery to the mills in the region, and the town supplied the workforce for both his factories, and the numerous mills and quarries operating in the immediate area.The Dent Hardware Company Factory Complex was listed on the National Register of Historic Places in 1986.