After finishing a two-year course at Philadelphia's Central High School, Yerkes began his business career at the age of 17 as a clerk for a local grain brokerage.

Relying on his bank president father's associations, his political acquaintances, and his own acumen, Yerkes became well-known as a businessman.

While serving as a financial agent for the City of Philadelphia's treasurer, Joseph F. Marcer, Yerkes risked public money in a large-scale stock speculation.

Left insolvent and unable to make payment to the City of Philadelphia, Yerkes was convicted of larceny and sentenced to thirty-three months in Eastern State Penitentiary.

[3] In an effort to improve his public reputation, Yerkes decided in 1892 to fund the world's largest telescope after being lobbied by the astronomer George Ellery Hale and University of Chicago president William Rainey Harper.

Yerkes renewed the campaign in 1897, and, after a hard-fought struggle, secured from the Illinois Legislature a bill granting city councils the right to approve extended franchises.

A partially reformed council and Mayor Carter Harrison IV, however, ultimately defeated Yerkes, with the swing votes coming from aldermen "Hinky Dink" Kenna and "Bathhouse" John Coughlin.

After the Chicago World's Fair in 1893, she tried to interest him in the works of Auguste Rodin, which were part of the loan exhibition of French art.

Pictures of Yerkes and his second wife Mary were painted by his favorite artist Jan van Beers (National Portrait Gallery, Washington, D.C.).