One of the many reasons Republicans need to try so hard to make up a new history at every opportunity. Sad thing, like evolution I thought it was common knowledge.

After the two terms of Democrat Grover Cleveland, the election of William McKinley in 1896 is widely seen as a resurgence of Republican dominance and is sometimes cited as a realigning election. McKinley promised that high tariffs would end the severe hardship caused by the Panic of 1893, and that the GOP would guarantee a sort of pluralism in which all groups would benefit. The Republicans were cemented as the party of business, though mitigated by the succession of Theodore Roosevelt who embraced trust busting. He later ran on a third party ticket of the Progressive Party and challenged his previous successor William Howard Taft. The party controlled the presidency throughout the 1920s, running on a platform of opposition to the League of Nations, high tariffs, and promotion of business interests. Warren G. Harding, Calvin Coolidge and Herbert Hoover were resoundingly elected in 1920, 1924, and 1928 respectively. The Teapot Dome scandal threatened to hurt the party but Harding died and Coolidge blamed everything on him, as the opposition splintered in 1924. The pro-business policies of the decade seemed to produce an unprecedented prosperity until the Wall Street Crash of 1929 heralded the Great Depression.

The New Deal coalition of Democrat Franklin D. Roosevelt controlled American politics for most of the next three decades, excepting the two-term presidency of Republican Dwight D. Eisenhower. African Americans moved into the Democratic Party during Roosevelt's time. After Roosevelt took office in 1933, New Deal legislation sailed through Congress at lightning speed. In the 1934 midterm elections, 10 Republican senators went down to defeat, leaving them with only 25 against 71 Democrats. The House of Representatives was split in a similar ratio. Republicans in Congress heavily criticized the "Second New Deal" and likened it to class warfare and socialism. The volume of legislation, and the inability of the Republicans to block it, soon elevated the level of opposition to Roosevelt. Conservative Democrats, mostly from the South, joined with Republicans led by Senator Robert Taft to create the conservative coalition, which dominated domestic issues in Congress until 1964. The Republicans recaptured Congress in 1946 after gaining 13 seats in the Senate and 55 seats in the House. -http://en.wikipedia.org/wiki/Republican_Party_(United_States)

So yeah, it was democrats who later became republicans, and the republicans switched to democrats basically.

It's even easier when you look at a map, south vs north and urban vs suburban more or less regardless what they are calling themself at any point in history.

Good supporting evidence can be found in the Party platforms of the time:

In 1932 and 1936 the Democratic Party platform had just a general nod to equality:

equal rights to all; special privilege to none

- the Democratic Party platform in 1940 had:

Our Negro citizens have participated actively in the economic and social advances launched by this Administration, including fair labor standards, social security benefits, health protection, work relief projects, decent housing, aid to education, and the rehabilitation of low-income farm families. We have aided more than half a million Negro youths in vocational training, education and employment. We shall continue to strive for complete legislative safeguards against discrimination in government service and benefits, and in the national defense forces. We pledge to uphold due process and the equal protection of the laws for every citizen, regardless of race, creed or color.

In 1944:

We believe that the country which has the greatest measure of social justice is capable of the greatest achievements.

We believe that racial and religious minorities have the right to live, develop and vote equally with all citizens and share the rights that are guaranteed by our Constitution. Congress should exert its full constitutional powers to protect those rights.

In 1948:

"The Democratic Party is responsible for the great civil rights gains made in recent years in eliminating unfair and illegal discrimination based on race, creed or color,"

"The Democratic Party commits itself to continuing its efforts to eradicate all racial, religious and economic discrimination."

"We again state our belief that racial and religious minorities must have the right to live, the right to work, the right to vote, the full and equal protection of the laws, on a basis of equality with all citizens as guaranteed by the Constitution."

"We highly commend President Harry S. Truman for his courageous stand on the issue of civil rights."

"We call upon the Congress to support our President in guaranteeing these basic and fundamental American Principles: (1) the right of full and equal political participation; (2) the right to equal opportunity of employment; (3) the right of security of person; (4) and the right of equal treatment in the service and defense of our nation."

"We pledge ourselves to legislation to admit a minimum of 400,000 displaced persons found eligible for United States citizenship without discrimination as to race or religion. We condemn the undemocratic action of the Republican 80th Congress in passing an inadequate and bigoted bill for this purpose, which law imposes no-American restrictions based on race and religion upon such admissions"

That progression (along with a largely anti-racist Republican party) culminated in Dixiecrat Southern congressmen (like Strom Thurmond) breaking off and forming their own racist "States Rights Democratic Party" whose 1948 party platform stated:

"We stand for the segregation of the races and the racial integrity of each race; the constitutional right to choose one's associates; to accept private employment without governmental interference, and to learn one's living in any lawful way. We oppose the elimination of segregation, the repeal of miscegenation statutes, the control of private employment by Federal bureaucrats called for by the misnamed civil rights program. We favor home-rule, local self-government and a minimum interference with individual rights."

"We oppose and condemn the action of the Democratic Convention in sponsoring a civil rights program calling for the elimination of segregation, social equality by Federal fiatt, regulations of private employment practices, voting, and local law enforcement."

"We affirm that the effective enforcement of such a program would be utterly destructive of the social, economic and political life of the Southern people, and of other localities in which there may be differences in race, creed or national orgin in appreciable numbers."

"We, therefore, urge that this Convention endorse the candidacies of J. Strom Thurmond and Fielding H. Wright for the President and Vice-president, respectively, of the United States of America."

The Republican party wasn't opposed to slavery.They believed Southern states had the right to maintain their slavery system but,didn't want slavery to migrate to the North.The Republican party didn't even oppose southern lynching laws.The Republican party was always the party of Big Business and their biggest concern was that the differences between the North and the South on the slavery issue and economics would eventually lead to the South seceding from the union.Wealth in the North was based on how many factories you owned and the South how many slaves you owned.The North had 5 times the factories than the South.The wealthy in the North didn't want to lose the Southern states as their base.America needs an FDR more today than ever.Democrats are opposed to "Free Markets" as was the North in the days of pre-Civil War Era days and as the South was not.Americas economic collapse today is proof of that.