Looking back on 2014, the watchdog group reported 35 executions in seven states, "the fewest number put to death since 1994."
The past year also saw 72 death sentences handed down -- a 40-year low and the fourth straight year in which there were fewer than 100 such sentences.
"Executions and sentences have steadily decreased, as Americans have grown more skeptical of capital punishment," the group said in a statement.
Botched executions involving lethal injections in Ohio, Oklahoma and Arizona, and the outcry they provoked, also contributed to the decline, it said.
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That was the fewest number of states to carry out executions in 25 years, the center reported.
The number of inmates on death row, which stood at 3,035 on October 1, also fell, continuing a trend going back to 2001.
And seven former death row inmates were exonerated of all charges -- the most since 2009, although on average it took 30 years for their innocence to be established.
"Not every year will show declines in every measure, but the overall pattern has been away from the death penalty," the centre said.
Worldwide, data on capital punishment indicates a trend "still firmly towards abolition," said Amnesty International in a report last March based on 2013 executions around the globe.
China by far carried out the most executions, numbering in the thousands, followed by Iran, Iraq, Saudi Arabia and the US, it said.
The Death Penalty Information Centre report appears at www.Deathpenaltyinfo.Org.