The name Mahanoy[Notes 1] is believed to be a variation of the Delaware word Maghonioy, or "the salt deposits".

[citation needed] Mahanoy City lies in a valley in the Pennsylvania Coal Region and was a major center of anthracite production; the area was embroiled in the Molly Maguires incidents.

[6][7][8] In 2010, the borough erected the Molly Maguire Historic Park, which features a Zenos Frudakis statue of a hooded miner on a gallows about to be hanged.

The borough's principal industries remain the mining and shipping of coal, although the demand for it has steadily declined since its peak in the late nineteenth and early twentieth centuries.

According to the United States Census Bureau, the borough has a total area of 0.5 square miles (1.3 km2), all land.

It has a warm-summer humid continental climate (Dfb) and average temperatures range from 24.3 °F in January to 69.3 °F in July.

[13] The hardiness zone is borderline between 5b and 6a, meaning that the approximate average annual absolute minimum temperature is -10 °F.