John Mills Van Osdel (July 31, 1811 – December 21, 1891) was an American architect who is considered the first Chicago architect. He is considered a peer of the most prominent architects in the history of Chicago. He has also done significant work throughout Illinois and the Midwest, although much of it no longer exists.
John M. Van Osdel was born in Baltimore, Maryland on July 31, 1811, the eldest son of carpenter James H. Van Osdel. During John's teenage years, James was temporarily paralyzed in an accident and the family thereafter struggled through poverty. To help the family, John began to work as a carpenter himself. He moved to New York, New York to work with his father once recovery was complete. In the city, Van Osdel found the Apprentice's Library, a catalogue of books related to carpentry and architecture. He returned to Baltimore in 1829 to work. The next year, Van Osdel began a profitable school for prospective draftsmen.
In 1836, after another relocation to New York, Van Osdel met New York State Assemblyman William B. Ogden. When Ogden moved west to Chicago, Illinois, he requested that Van Osdel follow him and design his house. After its completion, Van Osdel became engaged in steamboat construction, building the James Allen and George W. Dole. After construction began on the Illinois and Michigan Canal, Van Osdel built several water pumps and a horizontal windmill to aid with excavation. He returned to New York in 1840 to tend to his sick wife and to work as an associate editor for Rufus Porter's American Mechanic. The next year, after Van Osdel fell ill, he returned to Chicago.
Van Osdel built some of the city's first grain elevators upon his return. In 1843, he co-founded an iron foundry and machine factory with Elihu Granger. With his health continuing to fail, he left the partnership two years later to focus on his architecture. Van Osdel opened an office on Clark Street, the first architectural office in Chicago. During his time there he designed the Cook County Courthouse, the Chicago City Hall, and the Tremont House. He also designed a house for Governor Joel Aldrich Matteson which later saw use as the Illinois Executive Mansion. By 1859, Van Osdel was making over $32,000 in profit per year.