Northeast Blackout (August 2003)
A software bug and a tree hitting a transmission line triggered a cascade that cut power to 55 million people in the U.S. and Canada. It took days to restore service in parts of Ohio, Michigan, and the Northeast.
Congress and regulators created mandatory reliability standards with penalties for violations.
Utilities invested billions in grid monitoring and physical hardening.
Hospital power supply and backup systems became a priority after the blackout, the same rationale behind the Cherry Street duct bank upgrade.
