Between 1924 and 1999, 589 men and seven women were put to death in the gas chambers of various American states.
At its peak, eleven states had adopted this method: Arizona, California, Colorado, Maryland, Missouri, Mississippi, New Mexico, North Carolina, Nevada, Oregon, and Wyoming.
Eleven men have been gassed in five states since the resumption of executions in 1977, these being in Arizona (2), Nevada (1), North Carolina (2), California (2), and Mississippi (4).
The last lethal gas execution was that of Walter LaGrand in Arizona in 1999 (see below).
Of the states with capital punishment, only Arizona, California, Missouri, and Wyoming still, at least in theory, allow for the use of the gas chamber, and all offer lethal injection as an optional method.
The introduction of lethal gas executions ended the practice of hangings carried out by individual counties, and execution facilities and death rows became concentrated at State Penitentiaries.
Gassing has never been used by any other country as a means of judicial execution.
State-by-State Analysis in Chronological Order of Introduction
A comprehensive state-by-state record of executions by lethal gas:
| State | First Used (MM/DD/YY) | Last Used (MM/DD/YY) | Number of Executions | Males | Females | Number of Chairs in Chamber | Method Replaced |
|---|---|---|---|---|---|---|---|
| Nevada | 02/08/1924 | 10/22/1979 | 32 | 32 | 0 | 1 | Hanging |
| Colorado | 06/22/1934 | 06/02/1967 | 32 | 32 | 0 | Originally 3 | Hanging |
| Arizona | 07/06/1934 | 03/03/1999 | 37 | 37 | 0 | Originally 2 | Hanging |
| North Carolina | 01/24/1936 | 01/20/1998 | 197 | 195 | 2 | 1 | Electrocution |
| Wyoming | 08/13/1937 | 12/10/1965 | 5 | 5 | 0 | 1 | Hanging |
| California | 12/02/1938 | 08/24/1994 | 196 | 192 | 4 | 2 | Hanging |
| Missouri | 03/04/1938 | 02/26/1965 | 39 | 38 | 1 | 2 | Hanging |
| Oregon | 06/20/1939 | 08/20/1962 | 18 | 18 | 0 | 1 | Hanging |
| Mississippi | 03/03/1955 | 06/21/1989 | 35 | 35 | 0 | 1 | Electrocution |
| Maryland | 06/29/1957 | 06/09/1961 | 4 | 4 | 0 | 1 | Hanging |
| New Mexico | 01/08/1960 | 01/08/1960 | 1 | 1 | 0 | 1 | Electrocution |
| Total | — | — | 596 | 589 | 7 | — | — |
Note: Mississippi, North Carolina, and New Mexico used both the gas chamber and the electric chair at different times in the 20th century.
Origins and the First Execution: Gee Jon (1924)
Gassing was originally proposed by toxicologist Dr. Allen McLean Hamilton, who suggested it as an execution method that would be more humane than hanging or shooting, which were the choices offered to condemned men in Nevada in the early part of the 20th century.
Electrocution was seen as gruesome by the Nevada legislature, and so the new method was adopted, coming into law in 1921 in that state.
The original idea was to surprise the prisoner by gassing him in his cell as he slept without prior warning.
This proved impracticable, and thus the gas chamber, as such, was designed by Major Delos A. Turner, an army medical corps officer.
The first person to die in Nevada’s new gas chamber was Chinese-born Gee Jon, on February 8th, 1924, for the murder of Tom Quong Kee, a member of a rival gang.
His lawyers had fought a long battle in the courts to show that gassing was “cruel and unusual punishment” and as such was illegal under the 8th Amendment to the American Constitution.
This execution did not take place in a conventional gas chamber, but rather in an overly large room in a building in the prison grounds that had previously been the barber shop.
The gas was produced by vaporizing hydrocyanic acid using a mobile fumigating sprayer manufactured by the California Cyanide Company.
The execution commenced at 9:30 a.m. when Gee Jon was led from a holding cell and secured to one of the two rough wooden chairs within the room.
In the cold February temperatures, the hydrocyanic acid was reluctant to vaporize, and so it took some time for the concentration of gas to reach a lethal level.
Jon appeared to struggle a little after the gas was pumped in and then lapse into unconsciousness, but as no external stethoscope had been provided, he was left in the chamber for 30 minutes to ensure death.
The Nevada State Journal ran a banner headline the following morning, stating:
“Nevada Gas Death Law Held Success.”
Later, a conventional gas chamber was constructed.
Chamber Design and Construction: Eaton Metal Products
Most of America’s gas chambers were built by Eaton Metal Products in Denver, Colorado.
Their first was constructed in 1933 for Colorado and the last in 1955 for Maryland at a cost of $25,000. Colorado replaced its 1933 chamber with a new one in 1955.
Gas chambers are of welded and riveted steel construction, including the floor.
There is an adjoining Chemical Room where the chemicals are stored prior to use, and a Control Room.
Some chambers were built with a single chair—as in Colorado, Mississippi, Oregon, and Wyoming—and some with two chairs, as in Arizona, California, and Missouri (the latter was not constructed by Eaton). Both types were of otherwise similar pattern.
To prevent the cyanide gas from condensing, the execution area has to be kept heated to at least 80 degrees Fahrenheit, and any electrical fittings, e.g. lights, have to be explosion-proof, as hydrogen cyanide gas is explosive.
The gassing of Bonnie Brown Heady and Carl Hall on December 18th, 1953, was unique in that it was the only time that a man and a woman have been executed side by side by lethal gas.
The couple had abducted and murdered six-year-old Bobby Greenlease in Kansas City.
California and San Quentin Executions
Californian executions by lethal gas were carried out at San Quentin Prison.
The first gassings there took place at 10:00 a.m. on Friday, December 2nd, 1938, when Robert Lee Cannon and Albert Kessell were put to death simultaneously for the murder of prison warden Clarence Larkin, a guard, and two other inmates during an uprising at Folsom Prison.
The cost to the state of this for the cyanide and acid was $1.80.
The following Friday (12/9/1938), a further two inmates involved in this uprising were gassed, these being Wesley Eudy and Frederick Barnes. A fifth defendant, Edward Davis, was executed on December 16th.
Kessell seemed to die hard; it was reported that he:
“appeared to be trying to hold his breath. He was rigid and his hands gripped the arms of his chair as the gas hit him. He gasped: ‘It’s bad!’”
Cannon seems to have died easier.
Several witnesses complained about the proximity to the dying men over a lengthy period and that they had no mask or blindfold to hide their sufferings.
Ethel Leta Juanita Spinelli became the first woman to be executed in California and the first woman to die in a gas chamber when she was put to death for murder on November 21st, 1941.
The San Quentin gas chamber was constructed in a basement room and is a pale green painted octagonal metal box, 6 feet across and 8 feet high.
There is a 30-foot-high chimney outside to take the gas away.
The entrance is through a rubber-sealed steel door closed by a large locking wheel, and there are windows in five of the sides for the witnesses to view the execution.
Inside the California chamber are two identical metal chairs with perforated seats, marked “A” and “B.” (The twin chairs were last used in a double execution in 1962).
Two guards strap the prisoner into chair A, attaching straps across his upper and lower legs, arms, thighs, and chest.
They affix a Bowles stethoscope to the person’s chest so that a doctor on the outside can monitor the heartbeat and pronounce death.
Beneath the chair is a bowl filled with sulphuric acid mixed with distilled water to give a concentration of approximately 37%, with a pound of sodium cyanide pellets suspended in a gauze bag just above.
After the door is sealed, and when the warden gives the signal, the executioner in a separate room operates a lever that releases the cyanide into the liquid.
This causes a chemical reaction that releases hydrogen cyanide gas, which rises through the holes in the chair:
$$2\text{NaCN} + \text{H}_2\text{SO}_4 \rightarrow 2\text{HCN} + \text{Na}_2\text{SO}_4$$
When the reaction has finished, the gas reaches a concentration of around 7,500 ppm.
Witness Accounts and Medical Physiology
Prisoners are advised to take deep breaths after the gas is released, as this will considerably shorten their suffering.
Easy for the Warden to say, no doubt, but much harder for the prisoner to intentionally inhale the gas designed to kill them, even if they accept the logic of the advice they are given.
A typical witness’s view of gassing is as follows:
“At first there is evidence of extreme horror, pain, and suffocation. The eyes pop, the skin turns purple and the victim begins to drool”.
In medical terms, victims of cyanide gas die from hypoxia, which means the cut-off of oxygen to the brain.
The initial result of this is spasms, as in an epileptic seizure. Because of the straps, however, involuntary body movements are restrained.
Seconds after the prisoner first inhales, he or she will feel unable to breathe, but will not lose consciousness immediately.
“The person is unquestionably experiencing pain and extreme anxiety,”
according to Dr. Richard Traystman of Johns Hopkins University.
“The pain begins immediately and is felt in the arms, shoulders, back, and chest. The sensation is similar to the pain felt by a person during a heart attack, where essentially the heart is being deprived of oxygen.”
Traystman added:
“We would not use asphyxiation, by cyanide gas or by any other substance, in our laboratory to kill animals that have been used in experiments.”
A study of the execution records of 113 prisoners executed at San Quentin showed that the average time taken to kill them was 9.3 minutes.
The prisoner will usually lose consciousness between one and three minutes after the gas hits their face, and the doctor will pronounce them dead in around 8 to 12 minutes.
An exhaust fan then sucks the gas out of the chamber.
Next, the corpse is sprayed with ammonia, which neutralises traces of the cyanide that may remain.
After about half an hour, staff enter the chamber, wearing gas masks and rubber gloves.
Their training manual advises them to ruffle the victim’s hair to release any trapped cyanide gas before removing them.
Missouri Protocol (1938–1965)
Missouri used the gas chamber from 1938 to 1965, and the procedure was described as follows in a newspaper report in December 1953 relating how Bonnie Brown Heady and Carl Austin Hall would die:
“According to medical authorities, the doomed pair will feel a slight burning sensation around the nose then in less than a minute they will be unconscious. Actual death will follow in about ten minutes.”
In fact, it took 1¼ minutes for unconsciousness to set in and 9 minutes for them to die.
“After the lever releasing the cyanide is operated a puff of white vapour starts to rise. An involuntary stiffening occurs when the hydrogen cyanide gas hits the face and then in less than a minute the head falls forward – a signal of unconsciousness.
Muscles will alternately stiffen and relax, the head moving back and forth (typical symptoms of asphyxia).
Four minutes after unconsciousness, respiration usually stops and in another two to three minutes muscular action is halted. At this point they are unofficially pronounced dead.”
The cause of death is given as cerebral anoxia—lack of oxygen to the brain. Hydrogen cyanide cuts off oxygen to the lower nerve centres.
Modern Era (Post-Furman) Lethal Gas Executions
Five states carried out eleven executions by lethal gas after the resumption of the death penalty in 1977. These were Arizona, California, Mississippi, Nevada, and North Carolina.
Arizona (2 Executions)
Arizona moved from hanging to the gas chamber at the State Penitentiary in Florence for the execution of brothers nineteen-year-old Fred and eighteen-year-old Manuel Hernandez at 5:00 a.m. on July 6th, 1934.
A further 33 men would follow them to this fate up to 1963, when Manuel Silva became the last pre-Furman execution on March 14th of that year.
Arizona’s next execution occurred some 29 years later when Donald Eugene Harding was gassed on April 6th, 1992.
At 12:18 a.m., the sodium cyanide pellets dropped into the vat beneath Harding’s chair containing 6 quarts of distilled water and 6 pints of sulphuric acid.
Harding gasped, thrashing violently against the restraints, his face turning red and purple.
He continued to make spasmodic movements for ten minutes before becoming still, being declared dead at 12:29 a.m.
The horrific spectacle directly prompted television journalist witnesses to state they would never view another execution, and spurred Arizona to adopt lethal injection.
Walter LaGrand, a German national convicted of bank robbery and murder, became the last person in American history executed by lethal gas on March 3rd, 1999, choosing the gas chamber over lethal injection in protest against the death penalty.
It took eighteen minutes for LaGrand to die.
California (2 Executions)
California carried out two post-Furman gassings at San Quentin:
- Robert Alton Harris: Executed on April 21st, 1992, for the murder of two teenagers. The execution was interrupted by an eleventh-hour federal stay after Harris was already strapped in the chair, before the Supreme Court ordered the execution to proceed two hours later;
- David Edwin Mason: Executed on August 24th, 1994, for four murders, waiving his appeals and becoming the final person executed in San Quentin’s gas chamber.
Federal Judge Marilyn Hall Patel subsequently ruled the gas chamber unconstitutional under the 8th Amendment in Fierro v. Gomez (1994), a decision upheld by the 9th Circuit Court of Appeals, effectively ending the use of cyanide gas in California.
Mississippi (4 Executions)
Mississippi executed four men in its gas chamber at the State Penitentiary in Parchman between 1983 and 1989:
- Jimmy Lee Gray (September 2nd, 1983): Gray thrashed violently, gasping for air and repeatedly smashing his head against an iron pole behind the chair, prompting officials to clear the witness room after eight minutes;
- Edward Earl Johnson (May 20th, 1987);
- Connie Ray Evans (July 8th, 1987);
- Leo Edwards Jr. (June 21st, 1989).
Mississippi subsequently abandoned the chamber and replaced it with lethal injection.
Nevada (1 Execution)
Jesse Walter Bishop became the first and only person executed in Nevada’s post-Furman gas chamber at Carson City on October 22nd, 1979, having waived his appeals.
Nevada subsequently converted its chamber to lethal injection.
North Carolina (2 Executions)
North Carolina gassed two men at Central Prison in Raleigh post-Furman:
- David Lawson (June 15th, 1994): Refused to cooperate and repeatedly screamed, “I’m human!” as the gas rose;
- Ricky Lee Sanderson (January 30th, 1998): Waived his appeals and requested the gas chamber, becoming the last person executed by lethal gas in North Carolina before the state made lethal injection mandatory.
Frequently Asked Questions
Which state was the first to adopt the lethal gas chamber?
Nevada was the first state to authorize the gas chamber in 1921, carrying out the world’s first judicial execution by lethal gas on February 8th, 1924, when Gee Jon was put to death.
How does the chemical reaction inside a gas chamber work?
Sodium cyanide pellets are dropped into an earthenware crock situated beneath the execution chair containing a mixture of sulphuric acid and distilled water. The ensuing chemical reaction produces hydrogen cyanide ($HCN$) gas at a concentration of approximately 7,500 ppm, which rises through perforated holes in the chair seat.
What is the medical cause of death in the gas chamber?
Death occurs from cellular hypoxia and cerebral anoxia. Hydrogen cyanide inhibits cytochrome c oxidase within cellular mitochondria, halting cellular respiration and preventing cells from utilizing oxygen, which induces rapid unconsciousness and cardiac arrest within 8 to 12 minutes.
Who was the last person executed in a gas chamber in the United States?
German national Walter LaGrand was the last person executed by lethal gas in the United States, put to death in Arizona on March 3rd, 1999.
Which states still have the gas chamber as a legal option?
Only Arizona, California, Missouri, and Wyoming still retain statutory provisions for the gas chamber, exclusively as a secondary alternative if lethal injection is ruled unconstitutional or if the inmate committed their crime prior to statutory transition dates.
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