Episode 1 of 2

First Traffic Signals Installed

When: December 1868
Where: Parliament Square
Part of: World's first traffic signal lights installed in Westminster, London

First traffic signals showing red or green lights at night were installed in London in December 1868 to reduce police traffic control needs.

Traffic lights were first introduced in December 1868 on Parliament Square in London to reduce the need for police officers to control traffic. The first traffic signals showing a red or green light at night were installed outside the Houses of Parliament in London.

Sources

Traffic light Wikipedia, revision of 2026-09-01

Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.