American presidents have come close to apologizing to African-Americans for slavery, and several have spoken of the evil of what some historians call the peculiar institution. Soon, in a measure introduced by Rep. Steve Cohen, D-Tenn., the U.S. House of Representatives could formally apologize for slavery, Jim Crow segregation and the continuing legacy of discrimination against black people.

As of last week, due in part to a strategy devised to appeal more intimately to potential backers of his congressional resolution, Cohen had collected 90 co-sponsors.

In separate letters to members of the Congressional Black Caucus and the Jewish caucus and to members of the Missouri, Maryland, North Carolina, Virginia and New Jersey congressional delegations whose state legislatures have considered, or passed, similar resolutions, Cohen made his appeal.

"Slavery and Jim Crow laws were able to survive in our country because they were protected by the actions and acquiescence of the United States government, including Congress; we are still fighting their enduring legacies to this day," the letters say.