Amnesty International USA said in an annual report to be published Tuesday that capital punishment in the United States has become regional and fairly isolated event, with Texas accounting for roughly half of all executions.
"Only nine of the 36 states that retained the death penalty in 2008 actually carried out executions, and the vast majority of these executions took place in one region: the South," the US section of the London-based human rights group said in a statement.
"Texas accounted for, in essence, half (18 of 37) of the US executions in 2008," it added. And the southern state has carried out 12 of the 20 nationwide executions so far this year.
Other states including Virginia (east), Tennessee (south), Alabama (south), Ohio (north) and Oklahoma (south) also allow lethal injections -- the preffered method of execution, but in much smaller numbers.
New Mexico, also in the south, last week abolished capital punishment in its territory.
"Executions in the United States are increasingly a regionally isolated phenomenon," said Amnesty's Death Penalty Abolition Campaign director Sue Gunawardena-Vaughn.
"Elsewhere, concerns about cost, the possibility of executing the innocent and racial bias have led to a significant decline in support for capital punishment", she added.
While US opinion polls for years have shown a two-thirds support for lethal injections, this year the financial crisis has stressed the 10-to-one cost of execution compared to life imprisonment and made 10 states also consider its abolishment.
Anti-death penalty activists are hoping these states can tip the balance to more than half of the 50 states abolishing capital punishment in order to legally trigger its review on a national level.
In 2008, 2,390 people were executed around the world, nearly 75 percent of them in China, the Amnesty report said.