Clark played for the USA national team, and took five or more wickets on four occasions in the regular match against Canada, his best being 6/41 in the 1900 game in Manheim.

His practice centered on the "street railway, electric light, and power businesses" operated by E. W. Clark & Co., his family's financial firm.

[3][4] Percy and Elizabeth were the parents of eight children, including:[5] His wife died at their home in Ithan, Pennsylvania in June 1959.

Household staff included a houseman, cook, scullery maid, waitress, governess, a nurse, chambermaid, two gardeners, a farmer, and a driver.

They added a chauffeur's cottage and a barn, which supported a small working farm with seven cows, one horse, and 400 chickens.