He began his work for the court as a page, and, with the exception of two years, worked for it his whole life. Beginning his tenure as clerk when he was thirty-three years old, Cropley was the youngest clerk in Supreme Court history.
Cropley commenced his service with the court as a junior assistant, and, apart from a couple of years, devoted his entire career to it. He started his tenure as an entry-level clerk at the age of thirty-three, setting a record for being the youngest person to hold that position.