Elmer was formed on the dividing line of Pittsgrove and Upper Pittsgrove Townships and incorporated as a borough via public referendum January 24, 1893. The town was named after Judge Lucius Quintus Cincinnatus Elmer, a jurist respected state-wide, who had presided over Salem County's then-famous Treadway murder case and also produced the first compendium of New Jersey state statutes. As a Congressman, Elmer was largely responsible for securing a post office for the town.