From the Army Street location he published thousands of divided back cards, which had views of San Francisco, the Philippines, the Hawaiian Islands, comics, and early exaggerations of California fruits and vegetables.

[5] Mitchell bought the postcard business of California scenes and one set depicting Yellowstone National Park published by Albert Kayser of Oakland in 1898.

He printed postcards for a number of other publishers, including for photographer Charles Roscoe Savage, and Michael Rieder of Los Angeles.

[8][9] In 1921 Mitchell was listed as President with F. E. Edwards as Secretary of Dominion Oil Company, 3363 Army St., San Francisco.

In 1928-30 he is listed as Vice-president and treasurer of the Pacific Novelty Co. 579 Market St. S. F., Later in life he dealt in real estate and oil well leasing.