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Pat Sullivan, Associated Press
This photo taken June 12, 2013 shows empty and recently filled graves in the Joe Byrd Cemetery in Huntsville, Texas. The cemetery, commonly known as Peckerwood Hill, contains the remains of unclaimed Texas prison inmates.

HUNTSVILLE, Texas — Texas is approaching a grim milestone: It will soon execute the 500th prisoner since the death penalty resumed in the United States.

Barring a reprieve, Kimberly McCarthy will be executed by lethal injection on Wednesday night for the killing of her neighbor during a robbery in 1997.

Texas has accounted for nearly 40 percent of the more than 1,300 executions carried out since murderer Gary Gilmore went before a Utah firing squad in 1977 and became the first U.S. inmate executed following the Supreme Court's clarification of death penalty laws.

Virginia's death chamber is the second-busiest in the country, but the state is still nearly 400 executions behind Texas.