A few more thoughts about Reagan.
In the 1970s Democrats ruled the south. The Republican party didn't stand for much - Nixon was to the right of Clinton. The march of communism had slowed but still progressed, especially in South America.
The country was in a funk. Inflation was a problem from Nixon through Carter. Nixon tried a wage/price freeze. Ford tried WIN buttons (Whip Inflation Now). Carter didn't try much of anything. Neither Ford who came from Congress nor Carter who had no idea how Congress worked could accomplish anything.
Tax rates were outrageous. The progressive rates meant that you could never keep up with inflation. If the inflation rate was 12% (it was under Carter), you likely got 5%-6% wage increases but this pushed you into a new tax rate so you only saw 4%-5% of he increase (which was less than inflation anyway).
They came up with a new word for the economy - stagflation which meant a stagnant economy with high inflation.
Then came Reagan. Somehow he got his tax cuts through Congress. Between that and a painful recession, inflation dropped below 5% and never climbed back. By 1984 the economy was roaring. No one has mentioned stagflation since.
Reagan realigned the country. In the 1970s most people were registered as Democrats. Now most are independents who vote Republican. The South is now a Republican stronghold. Communism is nearly gone.