In the second half of the 19th century, after the conclusion of the Civil War and into the 20th century, there was a major influx of immigrants looking for work, as well as advances in technology. This boom happened faster than safety measures like labor laws and fire codes could advance to anything like what we have today. As a result, many of the most catastrophic fires and explosions in American history happened.
To identify the deadliest fires and explosions in U.S. history, 24/7 Wall St. reviewed data on fire casualties from the National Fire Protection Association. Fires and explosions were ranked on an estimated number of deaths. (It is important to note that death estimates for these disasters may sometimes vary by source.) Dates, casualty estimates, and locations came from NFPA.