The Economist maps out every American execution since 1976, when the Supreme Court announced the modern constitutional regime governing death penalty cases after effectively suspending all executions nationwide for four years. Over one-third of all executions during this period took place in Texas, for a total of 481 people killed by that state. Of the remaining, non-Texas executions, the overwhelming majority are clustered in a small group of southern states:
SOURCE: More Than One-Third Of All U.S. Executions Took Place In Texas | ThinkProgress.