Death Penalty Fast Facts

The Texas death chamber in Huntsville, Texas, seen in June, 2000, is where death row inmates are executed by lethal injection.

(CNN)Here's a look at the death penalty in the United States.

As of August 2017, capital punishment is legal in 31 US states.
According to the Death Penalty Information Center, 20 people were executed in the United States in 2016, the lowest number since 1991. The number of death sentences imposed was 30, a 39% decline from 2015's 40-year low.
There were 2,902 people on death row in the United States on October 1, 2016, the most recent date for which data is available.
    Since 1976, when the death penalty was reinstated by the US Supreme Court, 1,458 people have been executed (as of July 28, 2017).
    Since 1973, there have been 159 death row exonerations (as of April 19, 2017). Twenty-seven of them are from the state of Florida.
    Between January 1, 2017 and July 28, 2017, 16 executions were carried out in seven states, according to the Death Penalty Information Center.
    Federal Government:
    The US government and US military have 61 people awaiting execution. (As of July 25, 2017)
    The US government has executed four people since 1963.
    There are 54 women on death row in the United States (as of October 1, 2016).
    Sixteen women have been executed since the reinstatement of the death penalty (as of October 1, 2016).
    Twenty-two individuals were executed between 1985 and 2003 for crimes committed as juveniles.
    March 1, 2005 - Roper v. Simmons. The Supreme Court rules that the execution of juvenile offenders is unconstitutional.
    Since 1976, 282 individuals have been granted clemency for humanitarian reasons.
    For federal death row inmates, the president alone has the power to grant a pardon.
    1834 -
    Pennsylvania becomes the first state to move executions into correctional facilities, ending public executions.
    1838 - Discretionary death penalty statutes are enacted in Tennessee.
    1846 - Michigan becomes the first state to abolish the death penalty for all crimes except treason.
    1890 - William Kemmler becomes the first person executed by electrocution.
    1907-1917 - Nine states abolish the death penalty for all crimes or strictly limit it. By 1920, five of those states had reinstated it.
    1924 - The use of cyanide gas is introduced as an execution method.
    1930s - Executions reach the highest levels in American history, averaging 167 per year.
    June 29, 1972 - Furman v. Georgia. The Supreme Court effectively voids 40 death penalty statutes and suspends the death penalty.
    1976 - Gregg v. Georgia. The death penalty is reinstated.
    January 17, 1977 - A 10-year moratorium on executions ends with the execution of Gary Gilmore by firing squad in Utah.
    1977 - Oklahoma becomes the first state to adopt lethal injection as a means of execution.
    December 7, 1982 - Charles Brooks becomes the first person executed by lethal injection.
    1984 - Velma Barfield of North Carolina becomes the first woman executed since reinstatement of the death penalty.
    1986 - Ford v. Wainwright. Execution of insane persons is banned.
    1987 - McCleskey v. Kemp. Racial disparities are not recognized as a constitutional violation of "equal protection of the law" unless intentional racial discrimination against the defendant can be shown.
    1988 - Thompson v. Oklahoma. Executions of offenders age 15 and younger at the time of their crimes are declared unconstitutional.
    1989 - Stanford v. Kentucky, and Wilkins v. Missouri. The Eighth Amendment does not prohibit the death penalty for crimes committed at age sixteen or seventeen.
    1994 - President Bill Clinton signs the Violent Crime Control and Law Enforcement Act that expands the federal death penalty.
    1996 - The last execution by hanging takes place in Delaware, with the death of Billy Bailey.
    January 31, 2000 - A moratorium on executions is declared by Illinois Governor George Ryan. Since 1976, Illinois is the first state to block executions.
    2002 - Atkins v. Virginia. The Supreme Court rules that the execution of mentally retarded defendants violates the Eighth Amendment's ban on cruel and unusual punishment.
    January 2003 - Before leaving office, Governor Ryan grants clemency to all of the remaining 167 inmates on Illinois's death row, due to the flawed process that led to the death sentences.
    June 2004 - New York's death penalty law is declared unconstitutional by the state's high court.
    March 1, 2005 - Roper v. Simmons. The Supreme Court rules that the execution of juvenile killers is unconstitutional. The 5-4 decision tosses out the death sentence of a Missouri man who was 17 years old when he murdered a St. Louis area woman in 1993.
    December 2, 2005 - The execution of Kenneth Lee Boyd in North Carolina marks the 1,000th time the death penalty has been carried out since it was reinstated by the Supreme Court in 1976. Boyd, 57, is executed for the 1988 murders of his wife, Julie Curry Boyd, and father-in-law, Thomas Dillard Curry.
    June 12, 2006 - The Supreme Court rules that death row inmates can challenge the use of lethal injection as a method of execution.
    December 15, 2006 - Florida Governor Jeb Bush suspends the death penalty after the execution of prisoner Angel Diaz. Diaz had to be given two injections, and it took more than 30 minutes for him to die.
    December 17, 2007 - New Jersey Governor Jon Corzine signs legislation banning the death penalty in the state. The death sentences of eight men are commuted to life terms.
    December 31, 2007 - Due to the de facto moratorium on executions, pending the Supreme Court's ruling, only 42 people in the US are executed in 2007. It is the lowest total in more than 10 years.
    April 14, 2008 - In a 7-2 ruling, the Supreme Court upholds Kentucky's use of lethal injection. Between September 2007, when the Court took on the case, and April 2008 no one was executed in the US.
    March 18, 2009 - Governor Bill Richardson of New Mexico signs legislation repealing the death penalty in his state. His actions will not affect two prisoners currently on death row: Robert Fry, who killed a woman in 2000, and Tim Allen, who killed a 17-year-old girl in 1994.
    November 13, 2009 - Ohio becomes the first state to switch to a method of lethal injection using a single drug, rather than the three-drug method used by other states.
    March 9, 2011 - Illinois Governor Pat Quinn announces that he has signed legislation eliminating the death penalty in his state, more than 10 years after the state halted executions.
    March 16, 2011 - The Drug Enforcement Agency seizes Georgia's supply of thiopental, over questions of where the state obtained the drug. US manufacturer Hospira stopped producing the drug in 2009. The countries that still produce the drug do not allow it to be exported to the US for use in lethal injections.
    May 20, 2011 - The Georgia Department of Corrections announces that pentobarbital will be substituted for thiopental in the three-drug lethal injection process.
    July 1, 2011 - Lundbeck Inc., the company that makes pentobarbital (brand name Nembutal), announces it will restrict the use of its product from prisons carrying out capital punishment.
    July 7, 2011 - Humberto Leal Garcia Jr., a Mexican national, is executed by lethal injection in Texas for the 1994 kidnap, rape and murder of Adra Sauceda in San Antonio. Despite pleas from the US State Department and the White House, Texas Governor Rick Perry does not grant clemency and the US Supreme Court does not intervene.
    November 22, 2011 - Governor John Kitzhaber of Oregon puts a moratorium on all state executions for the remainder of his term in office.
    April 25, 2012 - Connecticut Governor Dannel Malloy signs S.B. 280, An Act Revising the Penalty for Capital Felonies, into law. The law goes into effect immediately and replaces the death penalty with life without the possibility of parole. The law is not retroactive to those already on death row.
    June 22, 2012 - The Arkansas Supreme Court strikes down the state's execution law, calling the form of lethal injection the state uses unconstitutional.
    August 7, 2012 - The Supreme Court allows the execution of Marvin Wilson, 54, a Texas inmate with low IQ.
    November 6, 2012 - A measure to repeal the death penalty in California fails.
    May 2, 2013 - Maryland's governor signs a bill repealing the death penalty. The legislation goes into effect October 1.
    January 16, 2014 - Ohio executes inmate Dennis McGuire with a new combination of drugs, due to the unavailability of drugs such as pentobarbital. The state uses a combination of the drugs midazolam, a sedative, and the painkiller hydromorphone, according to the state corrections department. The execution process takes 24 minutes, and McGuire appears to be gasping for air for 10 to 13 minutes, according to witness Alan Johnson, a reporter with the Columbus Dispatch.
    February 11, 2014 - Washington Governor Jay Inslee announces that he is issuing a moratorium on death penalty cases during his term in office.
    May 22, 2014 - Tennessee becomes the first state to make death by electric chair mandatory when lethal injection drugs are unavailable.
    May 28, 2014 - A judge in Ohio issues an order temporarily suspending executions in the state so that authorities can further study new lethal injection protocols.
    July 23, 2014 - Arizona uses a new combination of drugs for the lethal injection to execute Joseph Woods, a convicted murderer. After the injection, it reportedly took him nearly two hours to die. A state review board later rules that future executions will be conducted with a three-drug formula or a single drug injection if the state can obtain pentobarbital.
    September 4, 2014 - The Oklahoma Department of Public Safety issues a report about the botched execution of Clayton Lockett on April 29, 2014. Complications with the placement of an IV into Lockett played a significant role in problems with his execution, according to the report. It took 43 minutes for him to die.
    December 31, 2014 - Maryland Governor Martin O'Malley commutes the death sentences of the four last men in the state scheduled for execution. It is one of his final acts in office.
    January 8, 2015 - Ohio announces that it is reincorporating thiopental sodium, a drug which it used in executions from 1999-2011, into its execution policy. The state is also dropping the two-drug regimen of midazolam and hydromorphone.
    January 23, 2015 - The Supreme Court agrees to hear a case concerning the lethal injection protocol in Oklahoma. The inmates claim that the state protocol violates the Constitution's ban on cruel and unusual punishment.
    January 30, 2015 - The Ohio State Department of Rehabilitation and Correction announces it will delay the executions of seven death row inmates while searching for an adequate supply of drugs that complies with its new execution protocol.
    February 13, 2015 - Pennsylvania Governor Tom Wolf halts all executions in his state, citing the state's "error prone" justice system and "inherent biases" among his reasons for the moratorium. Philadelphia District Attorney R. Seth Williams later announces he has filed a petition to block Gov. Wolf halting executions, claiming the moratorium is an unconstitutional takeover of powers.
    March 23, 2015 - Utah Governor Gary Herbert signs legislation making the firing squad an authorized method of death if the drugs required for lethal injection are unavailable. The firing squad was last used in 2010 to execute a convicted murderer, Ronnie Lee Gardner.
    June 29, 2015 - The Supreme Court rules, in a 5-4 decision, that the use of the sedative midazolam in lethal injections is not a violation of the constitutional ban on cruel and unusual punishment. Midazolam is one of three drugs that are combined to carry out the death penalty in Oklahoma.
    October 19, 2015 - Ohio delays executions until 2017, citing difficulties obtaining the necessary drugs.
    August 2, 2016 - The Delaware Supreme Court rules the state's death penalty law unconstitutional. Attorney General Matt Denn later announces that he will not appeal the decision.
    April 2017 - Of the eight prisoners Arkansas had planned to execute before the state's supply of a lethal injection drug expires, four are put to death: Ledell Lee, Jack Jones, Marcel Williams, and Kenneth Williams. The other four - Jason McGehee, Stacey Johnson, Don Davis and Bruce Ward - receive stays of execution.