Here is an interesting article on voter caging. “Voter caging” is a term that refers to targeted efforts to suppress or intimidate selected groups of voters. This goes back to 1958… and, sadly, these efforts were directed against minority or Democrat-leaning constituencies by Republican state legislatures. These voter caging efforts would be accompanied by media campaigns alleging massive voter fraud when, in fact, the only evidence was a piece of non-forwardable mail to an old address. The person that would become the target of a voter caging effort may have had already moved and re-registered with the new address, but subtleties like that don’t make for good marketing.
The article itself covers voter caging up to 2004, but it remains a practice that the RNC makes part of the Republican national political strategy. And let’s be clear: these anti-fraud campaigns target minorities and Democrat-leaning constituencies, not Republican ones.
The efforts to disenfranchise minority voters are strengthened when Republicans in Congress vote to dismiss US Attorneys who refuse to pursue weak voter fraud cases brought to them by Republican Party operatives.

An excerpt:

Kentucky 2004

The Jefferson County, Kentucky Republican Party gave an early warning in the summer before the 2004 federal election that it planned a mass challenge program. The GOP announced in July that it would place Republican vote challengers in predominantly African American precincts during the November elections, just as they had done the previous year (in 2003, Jefferson CountyRepublicans placed challengers at 18 polling places in predominantly black districts).
The party went too far for some of its members. In August 2004, about a dozen Republicans gathered outside the Jefferson County Board of Elections to call for the resignation of the JeffersonCounty Republican Chairman, Jack Richardson. About half of the protesting Republicans were African American. An African American Republican candidate objected to the challengers, sayingthey would keep some of his supporters from the polls.
An African American Republican poll worker who had worked the polls for 13 years was angry that she had been replaced in the last election by a white Republican who did not live in the precinct.She reported that she visited several precincts to see who was working the polls and was surprised to find that virtually all of the locations were manned by white Republican poll workers.
http://www.projectvote.org/wp-content/uploads/2015/06/Caging_Democracy_Report.pdf