Why Tokyo, New York, and Los Angeles diverge so starkly
Tokyo achieves roughly 60% transit modal share for commuting because the city consolidated employment in the central district, built high-capacity rail infrastructure spanning centuries, and imposed severe parking restrictions that make driving expensive. New York achieves 30% transit share through a similar but less extreme approach, with strong subway coverage and high car costs offsetting lower density outside Manhattan. Los Angeles achieves 6% transit share because sprawling employment distribution made transit uneconomical, freeways enabled car-dependent development, and limited density means transit cannot achieve the frequency that makes it competitive.
These numbers reflect cumulative historical choices: Tokyo's development centered on rail corridors, New York's even before cars became common, while Los Angeles was developed during the automobile era with dispersed employment centers. A person in Tokyo without a car can access jobs easily; a person in LA without a car faces severe constraints. The choice was not inevitable but resulted from decades of planning decisions and investment patterns.
The self-reinforcing cycles of density and ridership
Transit modal share correlates almost perfectly with population density and job concentration. Dense cities with central employment support high transit ridership because distances are short, transit frequency is high, and cars are expensive. Sprawling cities struggle because jobs disperse over large areas, transit cannot reach all origins and destinations efficiently, and low density cannot support frequent service.
This creates a difficult dynamic: improving transit modal share requires density increases and employment centralization that take decades to achieve, while reduced car use would naturally emerge from that density. Many US cities attempt to increase transit ridership through service expansion alone without addressing the underlying density problem, a strategy that has failed to meaningfully shift modal share. The cities with successful high transit modal share did not start from car-dependent sprawl; they built their modern infrastructure on pre-car urban patterns or made major policy shifts (like Tokyo's postwar densification) to concentrate development.