Millerstown gained national notoriety during the Fries (Hot Water) Rebellion of 1798-99, as one of the hotbeds of opposition to the unpopular direct tax levied by the federal government under President John Adams. In April 1799, federal troops, sent to end local opposition to the tax, encamped in Schaeffer's woods, to the north of town along the Swabia Creek. George Schaeffer, David Schaeffer, and 'Grandy' Schaeffer Miller were among local supporters of this Rebellion.

Macungie is an Indian name signifying "eating place of bears" or simply "bear swamp" as it is translated today. The Lenape Indians (called Delaware Indians by the white settlers), who mined jasper in the quarries along the southeastern portion of the borough for knives and arrow points, named this area Mauck-Kuntshy because bears would come down into the valley to feed when food in the mountains was scarce. Other early spellings of Macungie included Machk-unschi, Machts Kunshi, Machts Kunski, Mackunshy, Macunjy, Maguntsche, Macongy, and Macungy.

In the 1914 History of Lehigh County, Pennsylvania, O. P. Knauss described the community as follows: "The town is situated on the northerly side of South mountain, in a valley which is unsurpassed in fertility and attractiveness by any other in many parts of the state.  From many points on the mountain, within a mile of the borough, there is presented a grand panoramic view of two-thirds of Lehigh county and parts of Berks and Northampton counties – a scene which never fails to incite wonder and delight.  The streets of the borough are all substantial, lined with beautiful shade trees and lighted at night by electric lights.  On account of the size and substantial character of the buildings, the cleanliness and compactness of the principal part, the town far surpasses most others of an equal population."