Brutal Cold Puts US Power Grids on Edge in Wake of Storm (2)

US power grids are under mounting pressure following a winter storm that unleashed deep cold and heavy snow and ice from Texas to Maine, driving up heating demand and raising the risk of blackouts.

The storm affected millions of people across the eastern two-thirds of the US, with more than 580,000 homes and businesses without electricity as of 7 p.m. New York time Monday as downed trees and ice ravaged local distribution lines, according to PowerOutage.us. More than half of the outages were reported in three states: Tennessee, Mississippi and Louisiana.

Power lines during a winter storm in Irving, Texas, on Jan. 25.

Photographer: Mark Felix/Bloomberg

So far, power grids have avoided large ...