A large molasses tank in Boston, Massachusetts, burst and a wave of molasses rushed through the streets , killing 21 people and injuring 150 others.

Molasses is a viscous byproduct, principally obtained from the refining of sugarcane or sugar beet juice into sugar. Molasses varies in the amount of sugar, the method of extraction, and the age of the plant. Sugarcane molasses is usually used to sweeten and flavour foods. Molasses is a major constituent of fine commercial brown sugar.

Boston is the capital and most populous city of the U.S. state of Massachusetts. The city serves as the cultural and financial center of New England, a region of the Northeastern United States. It has an area of 48.4 sq mi (125 km²) and a population of 675,647 as of the 2020 census, making it the third-largest city in the Northeastern United States after New York City and Philadelphia. The larger Greater Boston metropolitan statistical area has a population of 4.9 million as of 2023, making it the largest metropolitan area in New England and the eleventh-largest in the United States.

The Great Molasses Flood, also known as the Boston Molasses Disaster, was a disaster that occurred on Wednesday, January 15, 1919, in the North End neighborhood of Boston, Massachusetts.