Why did the Plan of Chicago fail to account for the impact of automobiles?

The Plan of Chicago, published in 1909 by Daniel Burnham and Edward Bennett, is a landmark in urban planning history that sought to address the complexities of the modern industrial city through a rational, interconnected regional vision. While the plan was visionary in its focus on infrastructure, open space, and the preservation of the lakefront, it did not account for the enormous impact of the [automobile].1

The plan's failure to anticipate the automobile's influence was largely a matter of timing and historical context. At the turn of the 20th century, the impact of the automobile was scarcely felt, and road improvements were primarily focused on city streets or feeder roads for railheads. By 1909, urban planning was still in its infancy as a governmental function, and the primary transportation focus for planners remained mass transit systems, such as subways and rail lines, which were being constructed to manage the rapid growth of cities like London, Paris, and New York. Consequently, the Plan of Chicago was designed around existing transportation realities rather than the transformative, congestion-inducing shift that mass automobile adoption would soon trigger.2314