In 1977, Oklahoma became the first state to adopt lethal injection as a means of execution, although it would be five years before Charles Brooks became the first person to be executed by lethal injection in Texas on December 2, 1982. Today in Today, All states that have the death penalty authorize execution by lethal injection. In this method, the condemned is usually strapped to a gurney and a member of the execution team places several heart monitors on this skin. Two needles (one as a spare) are then inserted into usable veins, usually in the prisoner's arms. Long tubes connect the needle to multiple IVs through a hole in a concrete block wall. The first is a harmless saline solution that kicks in right away. Then, at the warden's signal, a curtain is raised exposing the prisoner to witnesses in an adjoining room. So the process differs depending on whether the state uses a single-drug or multi-drug protocol.
In isolated drug executions, the prisoner is injected with an overdose of pentobarbital. In multi-drug executions, states begin with a sedative, formerly sodium thiopental, but more recently drugs like midazolam, designed to make the prisoner sleepy. Next, a paralytic drug, typically vecuronium bromide or pancuronium bromide, is injected, which paralyzes the entire muscular system and stops the prisoner's breathing. Eventually, potassium chloride flow stops the heart. Death occurs from anesthetic overdose and respiratory and cardiac arrest while the condemned person is unconscious.  Medical ethics prevent physicians from attending executions. However, a doctor will certify that the prisoner is dead. This lack of medical involvement can be problematic, as injections are often performed by inexperienced technicians or caregivers. If a member of the execution team injects the drugs into a muscle instead of a vein, or if the needle is blocked, extreme pain can result. Many inmates have damaged veins as a result of injecting drug use, and it is sometimes difficult to find a usable vein, resulting in long delays while the inmate remains strapped to the gurney. 
In search of a more humane method of execution than hanging, New York built the first electric chair in 1888 and executed William Kemmler in 1890. Other states soon adopted this method of execution. Electrocution is not the only method of execution used in any state today. Electrocution was the only method in Nebraska until the state Supreme Court ruled the method unconstitutional in February 2008. For execution in the electric chair, the person is usually trimmed, shaved, and strapped to a chair with belts crossing them across their chest, groin, legs, and arms. . A metal cap-shaped electrode is placed on the scalp and forehead over a sponge moistened with saline solution. The sponge must not be too wet or the saline solution will short out the current, nor too dry as it would have a very high resistance. An additional electrode is moistened with conductive gelatine (Electro-Creme) and stuck to a portion of the prisoner's leg, which has been shaved to reduce electrical resistance. The prisoner is then blindfolded.  After the execution team retreats to the observation room, the warden signals the executioner, who pulls a handle to connect the power supply. A jolt of between 500 and 2000 volts is emitted, which lasts about 30 seconds. The current rises and then dies off, at which point the body relaxes. Doctors wait a few seconds for the body to cool, then check to see if the prisoner's heart is still beating. If so, another shake is applied. This process continues until the prisoner is dead. The occupant's hands often grasp the chair and there can be violent movement of the extremities, which can result in dislocations or fractures. The tissue swells. defecation occurs. Steam or smoke comes out and there is a burning smell.  US Supreme Court Justice William Brennan once offered the following description of an execution by electric chair:
...the prisoner's eyeballs sometimes bulge out and land on [his] cheeks. The prisoner defecates, urinates, and often vomits blood and drool. The body turns bright red as the temperature rises, the prisoner's flesh swells and his skin stretches to the point of breaking. Sometimes the prisoner catches fire... Witnesses hear a loud, sustained sound like fried bacon, and the acrid-sweet smell of burning flesh pervades the chamber. [two]
At autopsy, the body is hot enough to blister when touched, and the autopsy is delayed while the internal organs cool. There are third degree burns with blackening where the electrodes hit the skin of the scalp and legs. According to Cook County Assistant Chief Medical Examiner Robert H. Kirschner, "The brain appears to be boiled in most cases." 
In 1924, the use of cyanide gas was introduced when Nevada sought a more humane way to execute its condemned prisoners. Gee Jon was the first person to be executed with lethal gas. The state attempted to inject cyanide gas into Jon's cell while he slept. This proved impossible because his cell was leaking gas, so the gas chamber was built.  Currently, five states allow lethal gas as a method of execution, but all have lethal injection as an alternative method. A California federal court found this method cruel and unusual punishment. In this method, the condemned is tied to a chair in an airtight chamber. Under the chair is a bucket of sulfuric acid. A long stethoscope is usually placed on the prisoner's head for a doctor to pronounce death outside the chamber. Once everyone has left the chamber, the room will be sealed. The warden then signals the executioner, who moves a lever that releases sodium cyanide crystals into the bucket. This causes a chemical reaction that releases prussic acid gas.  The prisoner is instructed to take a deep breath to speed up the process. However, most of the prisoners try to hold their breath and some fight.
The prisoner does not immediately lose consciousness. Clifton Duffy, a former San Quenton, California prison warden, said: "At first there are signs of extreme terror, pain and strangulation. The eyes fall out. The skin turns purple and the victim begins to drool."  Caryl Chessman, before he died in California's gas chamber in 1960, told reporters that he would nod if it hurt. Witnesses said he banged his head for minutes  According to Dr. Richard Traystman of the Johns Hopkins University School of Medicine, "The person will definitely experience pain and extreme anxiety... The feeling is similar to the pain a person feels during a heart attack, which is essentially around the heart lack of oxygen." The prisoner dies of hypoxia, the cutting off of the brain's oxygen supply.  At the autopsy, an exhaust fan removes toxic air from the chamber, and the corpse is sprayed with ammonia to neutralize all traces of cyanide. About half an hour later, paramedics wearing gas masks and rubber gloves enter the chamber. Their training manual advises them to ruffle the victim's hair to release the trapped cyanide gas before removing the deceased. 
Effective April 17, 2015, Oklahoma introduced death by nitrogen gas as an alternative to lethal injection when the necessary medication cannot be found or when that method is found unconstitutional. Nitrogen is a naturally occurring gas in the atmosphere and death would ensue if the prisoner were forced to breathe only nitrogen causing them to suffocate from lack of oxygen. Several other states have adopted nitrogen hypoxia as a backup method of execution, but as of May 2022, no state has issued a nitrogen execution protocol.
On March 23, 2015, firing squad was again authorized in Utah as a viable method of execution if and only if the state was unable to obtain the drugs necessary for an execution by lethal injection. Prior to this reauthorization, in Utah, firing squad was only a method of execution if the inmate chose it, before lethal injection became the only means of execution. Mississippi, Oklahoma, and South Carolina later approved a firing squad as an alternative method of execution.
The most recent execution by this method was that of Ronnie Gardner. At his own request, Gardner was executed by firing squad on June 17, 2010 in Utah. For execution by this method, the prisoner is usually tied to a chair facing an oval canvas with leather straps around the waist and head. Wall. The chair is surrounded by sandbags to absorb the prisoner's blood. A black hood is placed over the prisoner's head. A doctor locates the prisoner's heart with a stethoscope and places a white cloth circular target over it. In an area 20 feet away stand five gunmen armed with .30 caliber rifles loaded with single rounds. One of the shooters receives blanks. South Carolina's execution protocol calls for the use of three shooters, each receiving live rounds. Each of the shooters aims their rifle through a slit in the canvas and shoots the prisoner dead.  The prisoner dies as a result of blood loss caused by a ruptured heart or major blood vessel, or a ruptured lung. The person who was shot loses consciousness as the shock reduces the blood supply to the brain. If the shooters accidentally or intentionally miss the heart, the prisoner will slowly bleed to death. 
Up until the 1890s, hanging was the primary method of execution in the United States. Hanging was legal in Delaware and Washington before those states abolished the death penalty in 2016 and 2018, although both had lethal injection as an alternative method of execution.
In execution by hanging, the prisoner may be weighed the day before the execution, and an attempt is made using a sandbag of the same weight as the prisoner. This is to determine the length of "drop" needed to ensure a quick kill. If the rope is too long, the prisoner can be decapitated, and if it's too short, the strangulation can last up to 45 minutes. The rope, which should be 3/4 inch to 1 1/4 inch in diameter, should be boiled and stretched to eliminate feathering or coiling. The knot should be lubricated with wax or soap "to ensure smooth sliding," according to the 1969 U.S. Army Handbook. 
Immediately prior to execution, the prisoner's hands and legs are secured, blindfolded, and the noose placed around his neck, with the knot behind his left ear. Execution occurs when a trapdoor is opened and the prisoner falls through. The prisoner's weight should cause a rapid fracture dislocation of the neck. However, instantaneous death rarely occurs. 
If the prisoner has strong neck muscles, is very light, if the "halyard" is too short, or the rope is poorly placed, the fracture dislocation will not be rapid and death will occur by slow suffocation. In this case, the face swells, the tongue sticks out, the eyes open, the body defecates, and violent movements of the extremities occur.