Is this true?
Did the Democrats and Republicans change their ideologies from the 1800's to the present day?
Yes, both major American political parties underwent significant ideological transformations from the 1800s to today, with the most dramatic changes occurring in the mid-20th century.
The Democratic Party began as a party favoring limited federal government, states' rights, and agricultural interests. In the antebellum period, Democrats generally opposed federal intervention in state affairs, including slavery. This began shifting during the Progressive Era and accelerated dramatically under Franklin Roosevelt's New Deal in the 1930s, when Democrats embraced an active federal role in addressing economic and social problems. The most profound change came in the 1960s with the Civil Rights Movement, when Democrats under Lyndon Johnson championed federal civil rights legislation, completing their transformation into the party of liberal governance and social progressivism.
The Republican Party was founded in the 1850s as an anti-slavery party advocating for federal action to prevent slavery's expansion. Early Republicans supported strong federal government intervention, including during Reconstruction. They were the party of business and industrial development but also of civil rights enforcement. This began shifting in the early 20th century, and by the 1930s Republicans increasingly opposed New Deal expansion of federal power. The transformation accelerated from the 1960s onward, as Republicans adopted a "Southern Strategy" appealing to white voters opposed to civil rights legislation, while simultaneously embracing conservative social values and free-market economics.
Key factors driving these changes included industrialization, the Great Depression, World War II, the Civil Rights Movement, and shifting regional demographics. The parties essentially switched positions on federal power and civil rights over roughly a century.
This ideological realignment explains why Lincoln, a Republican, is celebrated by modern Democrats for his civil rights legacy, while many modern Republicans embrace states' rights positions historically associated with 19th-century Democrats.