"If the Republican party is the party of the white people, then the Democrat party must be the party of the black people. Right?"
no.. since blacks only make up about 12 percent of the population.
if republican party is all white people, then the democrat party is a percentag of whatever is left of those 70% that aren't republican.
anywhere from also all white, to a mix of every race... impossible to be all any other race, even hispanic since hispanics make up about 20%.
blacks and hispanics combined COULD be the whole democratic party, but its not seeming so.