The American power system has successfully withstood perhaps the most serious test in its history. For the first time, weekly electricity generation in the United States exceeded the 100 million megawatt-hour mark.

This historic milestone was reached due to extreme heat caused by the so-called heat dome, which covered an area home to more than 200 million people, Naked Science reports.

According to data published by the Edison Electric Institute (EEI), during the week from June 28 to July 4, 2026, the American power system generated a record 100 million megawatt-hours of electricity. For comparison, over seven days the country’s utility companies supplied consumers with an amount of electricity roughly twice New York City’s total annual consumption. This broke the previous record of 99.4 million megawatt-hours, set in July 2022. In addition, weekly generation was about 22% higher than the average level typical for the United States.

The main reason for the sharp surge in demand was the weather. A heat dome forms when a powerful high-pressure area acts like a lid, trapping hot air over a certain region and preventing it from dissipating. As a result, temperatures remain abnormally high for an extended period.

While Americans were celebrating Independence Day on July 4, a vast heat dome covered the central and eastern parts of the country. In many places, air temperatures exceeded 38°C, while the heat index reached about 46°C. Millions of air conditioners ran almost nonstop, creating an enormous strain on the power grid.