How has the Republican party transformed in values from Abraham Lincoln's era to current times?

The present day Republican Party is very different from the party of Abraham Lincoln as its core ideology has undergone radical change. The party was founded on the principle of opposition to the expansion of slavery. This was in reaction to the Kansas-Nebraska Act, which was designed to open up the Kansas and Nebraska territories to slavery. This would have gone against the Missouri Compromise, which forbade slavery north of 36°30'. During the Lincoln era,...

The present day Republican Party is very different from the party of Abraham Lincoln as its core ideology has undergone radical change. The party was founded on the principle of opposition to the expansion of slavery. This was in reaction to the Kansas-Nebraska Act, which was designed to open up the Kansas and Nebraska territories to slavery. This would have gone against the Missouri Compromise, which forbade slavery north of 36°30'. During the Lincoln era, the Party stood for the abolition of slavery and high tariffs to protect American industry; it introduced the income tax and generally favored big government. The party was dominated by moderate Protestants from the Northern states, African Americans, and owners of big businesses. Later on, the party also had an expansive foreign policy under William McKinley and Theodore Roosevelt. The Republicans dominated government between the Lincoln era and 1932, when Franklin D. Roosevelt came to power under the Democratic Party. The Republicans opposed the New Deal and this led to their defeat in most states in the country. This began the process of the changes in the Republican Party as it shifted from the party of big government to the party that wanted limited government. The party, however, advocated for African American rights and pushed hard for the Civil Rights Act in 1965. However, once the Democrats also accepted the idea of Civil Rights, the Republicans started to court the Southerners who opposed desegregation. The party thus began losing support in the more liberal North and amongst African Americans as it expanded in the South, where many abandoned the Democratic Party as it became more liberal. This process accelerated under Ronald Regan. Most Republicans admire Reagan mainly because he set the foundation of the present day Republican Party and completed the transformation that began after the Republican defeat by Roosevelt. Reagan consolidated the Conservative voter base by bringing together evangelicals and conservative Catholics to form the ‘moral majority’ by supporting various conservative issues such as opposing abortion. He established the Republican ideology of supporting low taxes and reducing government spending. He also had an aggressive foreign policy against the USSR and increased military spending. Since Reagan’s era, small government, low tax rates, focus on national security, opposition to large scale immigration, and appealing to a mainly white suburban voter base have been part of the core ideology of the Republican party until the rise of Donald Trump in 2016.