The U.S. Department of Energy warned that intense heat could heighten blackout risks across the PJM Interconnection, the largest U.S. electric grid, which serves 67 million people from Washington, D.C., to Chicago. Secretary Chris Wright authorized PJM to direct backup generation resources to operate as a last resort before declaring a level 3 energy emergency alert, a step that can precede rotating blackouts. Temperatures in Chicago, St. Louis and Washington, D.C., were expected to exceed 90 degrees Fahrenheit during peak demand. PJM also ordered generators on planned outages to report how quickly they could return to service. Separately, MISO forecast demand of about 121 gigawatts, close to its 127.1 GW record, and raised its normal reserve requirement amid warnings of tight conditions, possible plant outages and transmission congestion. In rural Missouri, Howell-Oregon Electric Cooperative urged customers to unplug unused devices and raise thermostats to reduce air-conditioning demand.