When Henry DeLand platted the town in 1876, he reserved the north and west-of-Downtown blocks for residential development. The earliest homes went up alongside the commercial core in the 1880s — including Henry DeLand's own 1886 home at 137 W Michigan Ave, which remains standing and operates today as the Henry A. DeLand House Museum [S23].
Through the 1890s–1920s, DeLand's Gilded Age wealth — drawn by the Stetson University campus, the winter-resort tourism economy, and the agricultural boom — built out the Old Northwest with the region's best examples of Victorian, Queen Anne, and Colonial Revival residential architecture. The Great Freeze of 1894–95 delayed but did not stop development; many of the largest homes date to the 1900s recovery decade.
Post-1930s, new residential construction shifted to streetcar-suburb patterns east and south of Downtown. The Old Northwest was largely complete by World War II and has remained remarkably intact thanks to preservation-overlay zoning and owner-stewardship of the individual properties.