The Ideal Laundry had a problem with smoke. Its boilers had run on coal for years, and Greenville city officials had been leaning on the company since before the war to do something about the soot. So in the summer of 1946 the laundry's manager, E.R. Haynie, went looking for an alternative. He toured industrial plants where the Superior Gas Corporation had installed propane systems, came back impressed, and signed contracts. The company first installed a small 500-gallon tank at Haynie's house. Then, in November, it put a 6,500-gallon system at the laundry. The plan was modern, clean, efficient. What no one quite understood at the time was that a propane leak in a closed basement would mix with air until it reached its flammability range, between 2.4 and 9.5 percent, and then a single spark from the boilers would do what coal smoke never could.

On the afternoon of November 19, the tank was filled to about half its capacity when workers noticed the leak. Haynie ordered the building evacuated and ran to the fire station a block away. Superintendent Trammel stayed inside to make sure the laundry employees got out. He almost succeeded. Mary Brown, Geraldine Simpson, and Mamie Earle were still inside when, minutes after the leak was first noticed, the propane in the basement ignited. The blast demolished all but one corner of the Ideal Laundry building. A Red Cross survey the following day found that nearly twenty nearby structures had been destroyed, most of them homes owned by African Americans. The Third Presbyterian Church across the street was one of roughly fifty other buildings severely damaged. A column of fire from the remaining propane reached almost six hundred feet into the air. People in Caesar's Head, Easley, Gaffney, Greer, and Liberty all looked toward Greenville and saw the same orange glow.

The northeast side of Greenville in 1946 was a Black neighborhood. The 1924 South Carolina Supreme Court decision in Allison v. Ideal Laundry mentioned 'nearly twenty' destroyed structures and lawsuits from homeowners, but the human geography behind that phrase rarely makes it into the official accounts. These were families whose houses were either blown apart by the blast or burned in the fire that followed. Many of them had built or bought those houses themselves, brick by brick, room by room, in a part of the city the white power structure had set aside for them. Several filed suit against Ideal Laundry seeking compensation. In 1949 a court held the laundry not responsible. The bankrupt Superior Gas Corporation was named the responsible party. Superior had already collapsed. The engineer who oversaw the installation killed himself shortly after the federal report came out. The homeowners, for the most part, got nothing.

Two federal investigators from the United States Bureau of Mines in Pittsburgh came down to Greenville to figure out what had gone wrong. Their report was straightforward: the system had been improperly constructed and installed. Their recommendations would become standard practice in the industry: keep large propane tanks well away from populated areas, install automatic or remote shut-off valves, require inspection by an impartial agency before any new system is put into service. Most of those rules are still in force today. Greenville Army Air Base sent soldiers to prevent looting overnight, while curious drivers from across the upstate caused traffic jams trying to get a look at the smoking crater. The blast is now mostly forgotten outside of disaster-history circles. The corner of Buncombe and Echols looks like an ordinary city block. But six people, including three Black women whose names are worth saying aloud, died there in less than a minute on a November evening, and the lessons learned from their deaths are now built into every propane tank in America.