Florida last month became the sixth state to adopt a resolution expressing "profound regret for the shameful chapter" in the state's history and promoting "healing and reconciliation among all Floridians."
Alabama, Maryland, North Carolina, New Jersey and Virginia had previously done so, and two other states - Nebraska and Missouri - are considering similar resolutions this year.
National black leaders applaud these gestures as an important step in reconciling the nation's long-standing racial differences, but caution that further actions, including reparations, are needed.
"I think it's very productive for states to look at their roles in the slavery movement. It's a good place to start," said Hilary Shelton of the National Association for the Advancement of Colored People . But he said, "unless further discussions follow, their actions will be viewed as very hollow."
All six state resolutions passed with near unanimous approval, although debates that preceded passage focused on whether an official apology amounts to an admission of guilt that could lead to calls for reparations - payments to the descendants of slaves for their suffering and lost economic opportunities.
The same issue has stymied efforts at the federal level to issue a national apology.
Last year, Tennessee Democrat Rep. Steve Cohen proposed that the federal government apologize for slavery and the so-called Jim Crow laws that victimized blacks after the Civil War. So far, Cohen's bill has not moved and requests for a presidential apology remain unanswered.
But at least one governor, Florida Republican Charlie Crist, has not shied away from the issue of reparations. When he signed Florida's apology resolution last month, Crist said he was open to considering financial reparations - not this year, but when the state's financial situation improves.
"I was floored. He had absolutely no hesitation," said author Ronald Walters, a leader in the push for reparations. "No other governor has ever done that."
In fact, several states have tried to put a lid on the issue by making clear their apologies are not a step toward reparations.
In Georgia, the state with the second largest pre-Civil War slave population, Gov. Sonny Perdue and other Republican politicians rejected a 2007 apology proposal, because they said it could make the state liable for financial reparations.
The states' apology movement comes as a reaction to a highly publicized, national push for reparations that peaked in 2002, Walters said. Since then, black state lawmakers decided reparations may not be possible any time soon, but an apology or expression of regret could start the process, he said.
In 2001, a group of black lawyers sued several U.S. insurance companies for having written policies on slaves for their owners. That same year, black leaders unsuccessfully urged President Bush to join a United Nations-sponsored conference on racism and reparations.
Several insurance companies later apologized for their role in enabling slavery, and California enacted a law calling on every insurance company in the state to research and report to the state its historical connections to the slave trade.
But the movement faded over the next four years, leading black lawmakers in several states to take a different approach, said Walters, who as a scholar at the University of Maryland, was instrumental in developing the state's 2006 legislative apology proposal.
Maryland in 2006 was the first state to consider an apology resolution, but Virginia - the state that once had the largest slave population in the country (490,865, according to an 1860 census) - in February 2007 became the first to enact a resolution.
"Virginia was the leader," said Democratic state Sen. Henry Marsh, III. "We started a dialog concerning slavery and race relations which we had hoped would happen. Other states immediately began calling us, asking how we did it," said Marsh, who sponsored the resolution.
Maryland Gov. Martin O'Malley (D) signed a resolution in March 2007 and governors in Alabama, New Jersey and North Carolina signed similar bills later in the year.
This year, Missouri supporters of an apology, which failed to pass the legislature last year, say the action would help heal racial wounds in a state that was so divided during the Civil War that it sent troops to both sides.
The Show Me state also is known for its 1856 court ruling denying a slave named Dred Scott citizenship rights. The decision, later upheld by the U.S. Supreme Court, led to enactment of the 13 th and14 th amendments to the Constitution, which abolished slavery and established legal rights for former slaves. As further evidence of Missouri's historical conflict over slavery, it later became the only state to enact its own emancipation law.
The recent apologies are not the first time states have taken action against slavery ahead of the federal government. In 1777, more than eight decades before President Lincoln issued the Emancipation Proclamation freeing slaves in the South, Vermont passed a law declaring the slave trade illegal. New York enacted a similar statute the following year.
"This is the moment for a national apology, because we have a historical first with a black (presidential) candidate running in the Democratic party," said Carol Swain of Vanderbilt University, who has urged President Bush to hold a Rose Garden ceremony to apologize for slavery.
"I expect states will continue to apologize, state-by-state, in a piecemeal, federalist fashion, and it might make it easier for the federal government to act," Swain said.