On Thursday, August 14, 2003 a massive power outage caused chaos across the Eastern United States and Canada hitting 8 U.S. states as well as major cities such as New York City and Ottawa. It is thought to be the worst power cut in US history, and has affected more than 50 million people. Traffic lights failed, underground railways were evacuated and people were trapped in lifts in offices and apartments. Since thousands of commuters were unable to get home, they had to spend the night sleeping on the streets. Shortly after 4:00 PM, the power went out and many areas remained in darkness well into the next day and even until Saturday morning. The outage began when several transmission lines owned by FirstEnergy in Ohio automatically shut down because they came too close to trees. Electricity had to be rerouted to other transmission lines, which, in turn, overloaded and failed. Since power plants and high-voltage lines must be in balance, the failures caused a ripple effect that shut down generators and lines across eight states. Because of a computer bug, FirstEnergy was not able to identify the problem. Today, the nation`s electrical system is a lot better equipped to prevent another big outage, but significant shortcomings remain, federal officials, grid operators and consultants agree.