In 1875, the groundwork for Penn Allen Glass started. Cyrus Shelly and Brothers opened their hardware business, which included a glass department. This newly developed glass department dealt with wholesale, retail and contract glazing. This was the start of Penn Allen Glass, incorporated in 1949.

The late Edward Haberman, one of the original C.Y. Shelly Bros. employees and shareholders, along with two partners, bought the entire business in 1955. They separated in 1964, with Mr. Haberman taking control of Penn Allen Glass, along with certain hardware operations.

Mr. Haberman's interest in the glass business was picked up by his son, the late Richard Haberman, who joined the company in 1947. Son-in-law, Donald McNabb, followed suit in 1949. Together, the "second generation" bought a glass company in Reading, Pennsylvania. It became a company branch in 1968 when the three men shared ownership of Penn Allen Glass.

Edward Haberman retired in 1972. Donald McNabb acquired sole ownership of the company in 1979, upon the untimely death of Richard Haberman. His two sons, James McNabb, who joined the company in 1974, and Thomas McNabb, who joined the company in 1982, have taken over the family business upon Donald's retirement in 1995.

In 2004 the McNabb brothers consolidated the operations under the same roof in Allentown, Pennsylvania, that Mr. Haberman began from. James oversaw the installation and glazing services, and Thomas the retail, fabrication and wholesale operations.

Today, effective 2009, Thomas has purchased James interest in the company and thereby closed the glazing services; concentrating on the fabrication and distribution services.

Together, along with the dedicated employees, Thomas McNabb continues to operate Penn Allen Glass by the same standards set by previous generations, and maintaining customer satisfaction is as much a way of life as it is an operating policy.