The basic definition of the Northwest side of Chicago would seem to be fairly clear. But before the annexation of large tracts of land north and south in 1889, Chicago city limits proper were confined to downtown and the near west side. The Northwest side as we know it today was populated as a series of villages which later became neighborhoods of Chicago : Irving Park and Jefferson Park to name a few. Some of these locales, which had independent post offices no longer exist even as neighborhood placenames. The story of the Northwest side is intertwined with commerce, industry and population growth,
The north branch of he chicago river gives some semblance of a path north west, this is reinforced by the Indian trails which later became planked roads: Milwaukee, and Elston. Later came the railroad lines and eventually expressways. Chicago's O'Hare field probably best defines the Northwest as a transportation hub of the city.