Gov. Bob McDonnell of Virginia enlarged democracy on Wednesday when he announced an order requiring the automatic restoration of voting rights for nonviolent offenders who have historically had to fight through a bureaucratic maze to gain access to the polls.

Governor McDonnell’s order, which could cover more than 100,000 people, reflects a growing awareness that disenfranchisement serves no rehabilitative purpose — and may, in fact, contribute to further criminal behavior by forcing former offenders to the margins of society.

In all, nearly six million Americans — about 2.5 percent of the voting-age population — are barred from voting by a confusing patchwork of state laws that strip convicted felons of the right to vote, often temporarily, but sometimes for life. Nearly two dozen states have softened their disenfranchisement policies since the late 1990s, with several states repealing or scaling back lifetime bans.

But the practice of barring offenders from the polls remains a pronounced and malignant problem in the South, where it was used starting in the late 19th and early 20th centuries to curtail the political power of African-Americans. During that period, state legislatures in the South went so far as to disenfranchise citizens for what they viewed as “Negro crimes,” like theft, while exempting defendants convicted of “white crimes,” including fighting in the streets and even murder.