Hallam (/ˈhɛləm/ HEL-əm) is a borough in York County, Pennsylvania, United States.

Before 1736, all parts of Pennsylvania west of the Susquehanna River, including present-day Hallam Borough and the surrounding Hellam Township, were land of the Iroquois.

In October 1736, the Proprietors of Pennsylvania received from the Five Nations deeds for the Susquehanna lands south of the Blue Mountains, including the borough and township.

In 1739, the Provincial Assembly passed a special act to empower Lancaster County to establish townships west of the river.

[6] According to the United States Census Bureau, the borough has a total area of 0.7 square miles (1.8 km2), all land.

[7] Hallam lies on the cusp of a humid subtropical climate zone and experiences four discernible seasons.

It receives an average of 43 inches (1,100 mm) of precipitation each year, with the wettest month being June.