: In 1920, Detroit police officer William Potts invented the three-color electric traffic light , adding an amber (yellow) light adapted from railroad signals.
: The first electric traffic signal in the U.S. appeared in Cleveland (1914) , controlling a mix of cars, streetcars, and horse-drawn carriages.
The evolution of traffic from the 1910s to the 2010s reflects a century-long race to manage increasing vehicle demand, safety challenges, and technological shifts. This guide outlines the major milestones in how we move and manage the roads. 1910s – 1920s: The Dawn of Regulation 100 Years Evolution of traffic - 1910s till the 2010s
: The first drunk driving law was enacted in New York in 1910 . 1930s – 1950s: Infrastructure & Computerization
Post-depression and war eras saw a focus on expanding road networks and basic automation. : In 1920, Detroit police officer William Potts
: In the 1930s, the first barrier crash tests were conducted by General Motors .
This era marked the transition from horse-drawn carriages to mass-produced automobiles. The evolution of traffic from the 1910s to
: The 20th century saw the creation of massive road networks, like the U.S. Federal-Aid Highway Act of 1921 , which paved the way for expansive interstate travel.