One of the most frightening industrial accidents in the U.S. occurred on this date in 1979 at the Three Mile Island Nuclear Power Plant on the Susquehanna River, south of Harrisburg, Pennsylvania. A cascade of alarms and emergency responses started when someone mistakenly cross connected air and water lines in the plant’s number two reactor. The plant reportedly came close to a hydrogen gas explosion and a meltdown of its uranium core, which would have caused extensive radiation contamination. The incident sparked a large-scale review of nuclear power safety. Today, there are 65 such plants operating 104 nuclear reactors in 31 states across the country, and employing about 38,000 workers. You can find more facts about America’s people, places and economy, from the American Community Survey, at <www.census.gov>.