"The old gray elephant, it ain't what it used to be"?
The shifting of allegiance between political parties was much more common during the 19th century than it is today. It took several years for political parties as we know them today to coalesce after the founding of the United States, and many parties formed and fell apart rapidly.
The Democratic Party (1828) is the oldest political party in the United States and one of the oldest grass-roots parties in the world. The Democratic party was a proponent for farmers across the country, urban workers, and new immigrants. It advocated westward expansion, greater equality among all white men, and opposition to a national bank.
The Republican Party emerged in 1854 from the former Whig Party to combat the Kansas Nebraska Act, which threatened to extend slavery into the territories, and to promote more vigorous modernization of the economy.
The Republican Party was based on northern white Protestants, businessmen, small business owners, professionals, factory workers, farmers, and African-Americans. It was pro-business, supporting banks, the gold standard, railroads, and tariffs to protect industrial workers and industry.
The shift in parties began in the second half of the 20th century - the southern states from Democratic to Republican, and New England and the West Coast states from Republican to Democratic.
African Americans, who had traditionally given strong support to the Republican Party since its inception as the "anti-slavery party," shifted to the Democratic Party, largely due to the economic opportunities offered by the New Deal relief programs in 1933-1938, and the advocacy of and support for civil rights by such prominent Democrats as former First Lady Eleanor Roosevelt.
Which makes me think this quote:
"I meant what I said and I said what I meant.
An elephant's faithful one-hundred percent!"
― Dr. Seuss, Horton Hatches the Egg
Hmm, maybe I need to go time traveling with Horton....