More than half of the states in the US have either abolished the death penalty or have formal suspensions in place, as the country’s use of the brutal punishment continues to wither on the vine.

When Virginia became the first southern state to scrap capital punishment in March, it raised to 23 the number of states that have abolished the practice outright. In a further three states, governors have imposed a moratorium on executions.

Virginia’s seismic shift away from judicial killings has created a death penalty-free zone on the north-east seaboard of the US that runs from Maine’s border with Canada down to the edge of the Carolinas. A similar zone now runs all the way down the west coast of the US.

The growing block of states where capital punishment is no longer welcome is one of the headline findings of the annual review of the Death Penalty Information Center (DPIC). The report contains nuggets that will make an abolitionist’s heart soar, including a record low number of new death sentences in 2021 (18) and the fewest executions carried out since 1988 (11).

But there is a powerful sting in the tail. As the fondness for judicial killings generally recedes, those states that are sticking with capital punishment are displaying grotesque aberrations in its application.

“The handful of states that continue to push for capital punishment are outliers that often disregard due process, botch executions, and dwell in the shadows of long histories of racism and a biased criminal legal system,” said DPIC’s executive director Robert Dunham.

Five states, together with the US government, judicially killed prisoners this year. Seven imposed new death sentences.

Three states have the dubious distinction of standing out in this year’s review – Alabama, Oklahoma and Texas. Between them they accounted for a half of all death sentences and most of the 11 executions.

Oklahoma botched its first execution in six years, that of John Grant who was observed convulsing and vomiting on the gurney. The Guardian revealed that another death penalty state, Arizona, spent thousands of dollars obtaining hydrogen cyanide for its gas chamber, the same lethal chemical used by the Nazis in Auschwitz.

Racism continues to leap out of the statistics, as it has since the early days of US capital punishment with its roots in slavery and racial terror lynchings. Ten of the 18 (56%) new death sentences were meted out to prisoners of colour, while the same percentage of death row inmates who were executed (six out of 11) were African American.

Reflecting a centuries-old distortion, more than three out of every four of the victims of this year’s murders ending in new death sentences were white. No non-white victim was involved in any case leading to a white person being condemned to death.

Horrors abound in other aspects of the behaviour of the rump of death penalty states. This was a year in which the callous disregard for the mental impairments of those prisoners put to death was on visceral display.

As Ngozi Ndulue, DPIC’s deputy director, pointed out, all but one prisoner executed this year had serious impairments including brain injury or damage, mental illness and intellectual disabilities, or had histories of gruesome childhood neglect and abuse.

“We are seeing fewer and fewer executions, but those that do occur demonstrate that the death penalty is not reserved for the worst of the worst, but the most vulnerable of the vulnerable,” she said.

Perhaps the most powerful argument of all against the death penalty is that it runs the risk of killing innocent people, and there was plenty of food for thought in that regard in 2021. Two death-row inmates were exonerated during the year, taking the total number of prisoners in the modern era who had been awaiting execution only to be found innocent to a staggering 186.

DPIC points out that the figure is equivalent for one exoneration for every eight executions that have been carried out in the past 50 years. Both this year’s exonerees, Eddie Lee Howard and Sherwood Brown, were from Mississippiand were cleared with the help of DNA testing after both had been on death row for 26 years.

The annual record for 2021 contains a hangover from an earlier era, in the form of the federal government’s flurry of executions in the dying days of the Trump administration. Three people on federal death row were killed in less than 10 days before Joe Biden’s inauguration, as part of Donald Trump’s rush to carry out 13 executions in six months.

Those who died in 2021 at the hands of the Trump administration were Lisa Montgomery, a profoundly mentally-ill woman who had suffered a lifetime of abuse tantamount to torture; Corey Johnson who was severely intellectually disabled; and Dustin Higgs who indisputably did not kill anybody.

Since Biden took office in January there have been no further federal executions and in June the US attorney general Merrick Garland announced a formal pause to give the Department of Justice time to review its policies.

Anti-death penalty campaigners have been hoping the Biden administration would end the federal death penalty and commute sentences of the remaining 45 federal death row inmates to life imprisonment. So far, there has been no sign of that happening.