[margaret h]

MLK actually WAS a Republican although he later changed his registration to Democrat.
The reason is that Democrats, who have a long history of identity politics when it suits them, mostly refused to register blacks until some time in the 1960s. Any blacks who wanted to vote were registered without prejudice by the Republican Party, the party of Abraham Lincoln.
The 1964 Civil Rights Act was only passed by the efforts of the Senate Minority Leader GOP Sen. Everett Dirksen, who got the rest of the Senate GOP members to support it despite oppostion from Democratic Senators including Al Gore.
President John F Kennedy voted against the 1957 Civil Rights Act when he was a Senator. The governors who kept the schools segregated were Democrats.

Blacks should read their history instead of blindly listening to the Democrats to whom they really owe very little. Younger Democrats should also rethink their prejudices. They have been lied to for decades.