Nation IN BRIEF : THE WEST : Outage in 15 States Affected 2 Million

A power outage that blackened the West, affecting 2 million people from Canada to Mexico, began with an Idaho transmission line that short-circuited when electricity jumped to a tree that had grown too close, investigators said. The outage in that line, combined with record power demands during hot weather, caused a ripple effect July 2 that cut power to 15 Western states and parts of Canada and Mexico, said Corry Alsberg, a spokeswoman for a group of regional utilities. The tree, which has since been removed, triggered the flashover in a remote area about 100 miles east of the Kinport substation in southeastern Idaho. The Idaho line carries 345,000 volts and stretches from the Jim Bridger generating plant near Rock Springs, Wyo., to the substation.