During his lifetime, Harry C. Trexler contributed a great deal to the growth and quality of life in the City of Allentown and the surrounding County of Lehigh. Born in 1854, Harry Clay Trexler attended area public schools and later the Tremont Seminary in Norristown. After his father's death, Trexler and his brother expanded the family business into one of the largest lumber companies in the East. In 1885, Trexler married the daughter of a wealthy tanner, Mary M. Mosser. The couple had no children.

In 1897, Harry Trexler, George Ormrod, and Colonel E. M. Young organized the Lehigh Portland Cement Company which became one of the largest cement producers in the world. Trexler also was involved with public utilities including water, electricity, public transportation and telephones. He held seats on several corporate boards as well as trusteeships at three area hospitals, two colleges and a university.

Trexler served on the staffs of six governors of Pennsylvania. In 1911, he was appointed Colonel and Quartermaster General of the Pennsylvania National Guard. In 1916, he served during the mobilization of troops on the Mexican border and in 1917 prepared troops for service in World War I. He retired in 1918 having achieved the rank of Brigadier General.

Trexler devoted much of his time to a variety of agricultural pursuits including a trout hatchery, poultry farms, potato and grain farms, orchards, alfalfa dehydrating plants, and a sheep ranch. From more than 1,100 acres, Trexler established a game preserve for buffalo, elk and deer. This property, known as the Trexler-Lehigh County Game Preserve, was conveyed to the county after the General's death.

Instrumental in planning the city's extensive park system, Trexler served as chairman of Allentown's first planning commission. At his own expense, Trexler hired a renowned landscape architect to beautify a vacant city lot, which became West Park. The development of the Little Lehigh Parkway began in 1931 with Trexler's donation to the city of 30 1/2 acres of the trout hatchery property. Trexler's summer home, Springwood Farm, was conveyed to the City of Allentown after his death and is now known as Trexler Memorial Park.

Trexler contributed money to all public fundraising campaigns fro hospitals, colleges, charity and welfare organizations, often serving as chairman of the campaigns. Beginning in 1914 and continuing for every year until his death, he and Mrs. Trexler sponsored Romper Day, a children's festival in the City of Allentown.

As a result of injuries from an auto accident, Harry Clay Trexler died on November 17, 1933, leaving a residuary estate of approximately ten million dollars. His will directed that the residue should be held upon a perpetual trust, the income from which would benefit his wife during her lifetime and the citizens of Lehigh County, Pennsylvania after her death. Mary Trexler's will complemented that of her husband, providing for her estate to be merged with his. The charitable trust, now known as the Harry C. Trexler Trust, came into being after Mary Trexler's death on December 20, 1934. It was settled with an initial corpus of nearly twelve million dollars.

At present, the trust's assets are valued at about $100 million dollars. In 2003, more than $4 million was awarded. The single largest beneficiary was the City of Allentown at $1.36 million. The remaining was distributed among various Lehigh County charities.

The five trustees are Dexter F. Baker, former CEO of Air Products, Kathryn Stephanoff, Director of the Allentown Public Library, Daniel G. Gambet, O.S.F.S., President Emeritus of DeSales University, Malcolm J. Gross, Senior Partner of Gross, McGinley, LaBarre & Eaton, and Robert C. Wood, Chairman of the Wood Company.

During the 70 years of its operation, the trust has distributed over $85 million to Lehigh County charities including $27.3 million to the City of Allentown. General Trexler's generosity toward the citizens of Allentown and Lehigh County continues through his trust.