A recent letter celebrating the history of the Republican Party makes the common mistake of overlooking the major parties’ mid-20th century shift in orientation on matters of race. The Grand Old Party does, indeed, have a distinguished record, but it was not responsible for the Civil Rights Act of 1964.
That act was passed by liberals and moderates of both parties. The Democrats who opposed it were largely Dixiecrats such as Strom Thurmond and Robert Byrd. (Thurmond, like many Southerners, soon afterward changed his party affiliation to Republican. Byrd remained a Democrat and later repudiated his opposition to the bill.)
The Republicans who supported it were moderates such as Everett Dirksen.
But the bill itself was a Democratic project, conceived by President John Kennedy and piloted through Congress in the wake of his death by the legendary political skills of Lyndon Johnson. It was passed partly as a tribute to Kennedy.