No, 200 politicians didn't switch -- that's a laughably high bar -- but there were plenty.
3. Rep. William C. Cramer, the first GOP rep in Florida, for instance, switched from the Democrats in 1949, won election in 1954, urged Ike to withdraw troops from Little Rock in 1957 and voted against the Civil Rights Act of 1964.
Segregationist Rep. Albert Watson publicly backed Goldwater in 1964. In retaliation, House Dems stripped him of his seniority.
He then went on to head Nixon's Mississippi campaign and then win elections as a congressman and then senator.
Colmer chose Lott to succeed him in 1972, but had him run as a Republican. nytimes.com/2002/12/15/us/…
Again, this isn't what historians stress in party realignment, but yes, it happened.
Here's a terrific new book on it, by the way:
19. SC Rep. Arthur Ravenel Jr.
20. SC Rep. Floyd Spence
21. Texas Rep. Jack Cox
22. Mississippi Sen. Stanford Morse
23. Alabama Rep. Albert Goldthwaite
24. Louisiana Rep. Roderick Miller
25. South Carolina Sen. Marshall Parker
Again, looking at elected officials is the worst way to measure these changes. (And, of course, that's why D'Souza insists on doing it that way.)
There were efforts to get more S. Dems to switch (see below), but without the Thurmond Deal, few wanted to switch.
What did change were public perceptions of the parties on matters of civil rights, as @edsall noted here.
Well, if you want more on this, check out Merle Black and Earl Black's classic: amazon.com/Rise-Southern-…