In Boston, Massachusetts, a fire in the Cocoanut Grove nightclub kills 492 people.

The Cocoanut Grove fire was a nightclub fire which took place in Boston, Massachusetts, United States, on November 28, 1942, and resulted in the deaths of 492 people. It is the deadliest nightclub fire in U.S. history, and the second-deadliest single-building fire (after the Iroquois Theatre fire).

The Cocoanut Grove was one of Boston's most popular nightspots, attracting many celebrity visitors. It was owned by Barnet "Barney" Welansky, who was closely connected to the Mafia and to Mayor Maurice J. Tobin. Fire regulations had been flouted: some exit-doors had been locked to prevent unauthorized entry, and the elaborate palm tree dcor contained flammable materials. The air-conditioning used flammable gas due to wartime shortage of freon.

During the first Thanksgiving weekend since the U.S. had entered World War II the Grove was filled to more than twice its legal capacity. The fire was initiated by an electrical short and fueled by methyl chloride in the air conditioning unit. Flames and smoke spread rapidly through all areas of the club, and people were unable to escape due in part to locked exit doors. Blame was directed at Welansky for violation of standards; he served nearly four years in jail before being released just weeks before his death.

Local hospitals were especially well prepared to treat the casualties having been rehearsing emergency drills in response to possible wartime attacks on the East Coast. The crisis demonstrated the value of the new blood banks and stimulated important advances in the treatment of burn victims.

Following the tragedy, many new laws were enacted for public establishments, including the banning of flammable decorations, a provision that emergency exits must be kept unlocked (from the inside), and that revolving doors cannot be the only exit.

Boston (US: , UK: ), officially the City of Boston, is the capital and most populous city of the Commonwealth of Massachusetts in the United States and 24th-most populous city in the country. The city proper covers about 48.4 square miles (125 km2) with a population of 675,647 in 2020, also making it the most populous city in New England. It is the seat of Suffolk County (although the county government was disbanded on July 1, 1999). The city is the economic and cultural anchor of a substantially larger metropolitan area known as Greater Boston, a metropolitan statistical area (MSA) home to a census-estimated 4.8 million people in 2016 and ranking as the tenth-largest MSA in the country. A broader combined statistical area (CSA), generally corresponding to the commuting area and including Providence, Rhode Island, is home to some 8.2 million people, making it the sixth most populous in the United States.Boston is one of the oldest municipalities in the United States, founded on the Shawmut Peninsula in 1630 by Puritan settlers from the English town of the same name. It was the scene of several key events of the American Revolution, such as the Boston Massacre, the Boston Tea Party, the Battle of Bunker Hill, and the siege of Boston. Upon American independence from Great Britain, the city continued to be an important port and manufacturing hub as well as a center for education and culture. The city has expanded beyond the original peninsula through land reclamation and municipal annexation. Its rich history attracts many tourists, with Faneuil Hall alone drawing more than 20 million visitors per year. Boston's many firsts include the United States' first public park (Boston Common, 1634), first public or state school (Boston Latin School, 1635) first subway system (Tremont Street subway, 1897), and first large public library (Boston Public Library, 1848).

Today, Boston is a thriving center of scientific research. The Boston area's many colleges and universities make it a world leader in higher education, including law, medicine, engineering and business, and the city is considered to be a global pioneer in innovation and entrepreneurship, with nearly 5,000 startups. Boston's economic base also includes finance, professional and business services, biotechnology, information technology and government activities. Households in the city claim the highest average rate of philanthropy in the United States; businesses and institutions rank among the top in the country for environmental sustainability and investment. The city has one of the highest costs of living in the United States as it has undergone gentrification.