The US electrical grid is better managed and more flexible a decade after its largest blackout, but remains vulnerable to increasingly extreme weather, cybersecurity threats and stress caused by shifts in where and how power is produced.

The industry has mostly addressed the failures blamed on a tree branch in Ohio that touched a power line and set off outages that cascaded across eight states — and blacked out the Big Apple — and parts of Canada the afternoon of Aug. 14, 2003, causing 50 million people to lose power. Grid operators who didn’t initially realize what was happening now have a nearly real-time view of the system and are better equipped to stop problems from growing.