Though located outside the Borough limits, the Hummelstown Brownstone Company contributed more than any other single industry to the growth of Hummelstown. The brownstone was quarried in a ridge in South Mountain, 2 ½ miles south of Hummelstown. The time of operation was from 1860 until 1929 when the use of a lightweight concrete composition stone and reinforced concrete became favorable to using natural stone. At the peak of its operations, the Brownstone Company employed over 600 people. The original quarry was on the Berst property and evidence exists in the form of early tombstones, dating the quarrying activities to the early 1700s. It is said that the stone for the enlargement of the Union Canal in 1853, as well as the bridges and culverts on the Lebanon Valley Railroad, was quarried here. Henry Brown of Harrisburg, operating under the name of the Pennsylvania Brown Freestone Company, quarried this stone commercially, and in 1866 erected a stone cutting mill in Hummelstown where stone was prepared for shipment to various cities, including Philadelphia, Lancaster, Reading, and Pottsville. In 1867 Allen Walton of Philadelphia took over the operations and by 1881 had assumed ownership. In 1886 Walton built a 4-mile railroad connecting the quarries with the Reading Railroad at Brownstone Station. Over the years, the company supplied This plaque donated in memory of Jean Alter by the family.
stone for buildings in St. Petersburg, Florida, the "Brownstones" of New York, the Bureau of Engraving and Printing in Washington, D.C., and notably, Union Station in Indianapolis, giving evidence of its widespread reputation. The Walton Mansion, built by Allen Walton and presently the American Legion-Post 265 facilities at the east end of town, is one of the many remaining "Brownstone" buildings in Hummelstown.
Brownstone is still quarried today in Pennsylvania and is visible here as the walls of the planters for the 1997 Square Renovation Project.