The man behind gerrymander did not pronounce his own name the way almost everyone now says the word. Elbridge Gerry said it with a hard "g," as in "get."
Gerry was a Founding Father. He signed the Declaration of Independence, and in 1812 he was governor of Massachusetts. That year his Democratic-Republican party redrew the state senate districts. The new lines broke up Federalist strongholds, and one district in Essex County came out in an odd, sprawling shape.
Federalists saw an animal in it. The best-known story places the moment at a Boston dinner party. Smithsonian magazine says the illustrator Elkanah Tisdale sketched the district. A guest said it looked like a salamander, and the poet Richard Alsop answered, "Gerry-mander." The Massachusetts Historical Society puts the dinner at the home of the merchant Israel Thorndike. Wikipedia is more cautious. It says historians suspect Federalist newspaper editors coined the word, but no definitive evidence shows who said it first.
What is certain is where it was printed. The Boston Gazette used "Gerry-mander" on March 26, 1812. The cartoon gave the district wings, claws and a serpent's head, and called it a new species of monster.
Gerry himself may not have liked the map. His son-in-law later said Gerry found the plan "highly disagreeable." He signed it anyway. It did not save him: the uproar helped the Federalist Caleb Strong defeat him in the 1812 election. He then became James Madison's vice president and died in office on November 23, 1814.
His name outlived him in a way he would not have chosen. By the 1820s gerrymander was a verb for drawing districts to favor one party. The hard "g" slowly gave way, and the soft "j" pronunciation is now dominant.
The word also proved easy to copy. Wikipedia lists later coinages built on other politicians' names, such as "Perrymander" for Texas governor Rick Perry and "Bjelkemander" for the Queensland premier Joh Bjelke-Petersen.