McKim was elected as a Democrat to the Seventeenth Congress to fill the vacancy caused by the resignation of Samuel Smith.

On the same day, McKim was elected as a Jackson Republican to the Eighteenth Congress to fill the vacancy caused by the resignation of Representative-elect Smith and served from January 4, 1823, to March 3, 1825.

McKim was a "wealthy sea-dog and merchant"[4] and a leader in the commercial and industrial life of Baltimore.

Among other businesses he had a copper warehouse on Gay street in Baltimore,[5] and operated a steam flour mill.

This article incorporates public domain material from the Biographical Directory of the United States Congress