Did the connection of party and ideology lead to red states and blue states becoming a thing?
Not exactly. I think Ideology has been broadly constant among the population on the major political threads, while the parties have changed.
Ideology is traditionally the greatest determining factor in how folks vote. Not Party. There is latency, and a tipping point factor as we've seen with Fiscal Conservatives, some of whom are still loyal to the GOP, other ideological differentiators like Social Conservatives have faced more clear tipping points when they've jumped from one party to the next.
Typically Parties support different ideologies in an attempt to form their majorities and propel them into power. Over time their platforms have shifted as they try to attract a larger number of voters, when this occurs the voters change parties traditionally. There have been times when shifting ideology has lead to large scale shifts among the voters.
Let's take slavery and civil rights as the major political issue of the first 150 years of our nation's existence. Social Conservative Southern voters were strong Democrats over the first 150 years. When they tried to secede from the union the liberal even extreme left "radical" Republican party lead by Abraham Lincoln opposed them. African American people rewarded the Republican Party with their loyalty for the next 100 odd years.
Nov 1963 Democrat President Kennedy is assassinated, his VP is LBJ a former socially conservative Democratic Senator from Texas, up to then a strong and consistent segregationist with 3 decades of congressional voting history, takes over Kennedy's socially progressive but otherwise conservative machine. LBJ informed he cannot win a national election because he is too associated with segregation flips the parties. LBJ champions and passes the most ambitious civil rights bill in the nations history, 1964 civil rights bill. With this act white souther socially conservative voters leave the Democratic Party. They are cemented into the Republican party by Ronald Reagan in 1980 with his support for socially conservative issues including pro-life, and moral majority positions.
Reagan tied together Fiscally Conservative Voters, With Socially Conservative Voters, with Foreign Policy Hawks and Libertarians for the first time. Since then of coarse we can make the case the Socially Conservative members of Reagan's alliance have basically taken over the party. The massive unsustainable increase in spending and deficits Reagan and all subsequent Republicans have pursued typically offend fiscal conservatives, while find much greater support for social conservatives who are ideologically ambivalent on fiscal policy in all but speech.
As the Republicans with this Conservative quartet got more popular mainstream democrats have largely copied many of their planks except a handful of differentiators. And now we have Donald Trump, a non traditional Republican who basically won the Presidential election against Hillary Clinton by moving to the Left and capturing many traditional Democratic voters. Blue Collar manufacturing workers are probable Trump's greatest and most loyal constituency. Traditionally Democratic voters who moved to trump after decades of watching Democratic candidates support issues first championed by Republicans.
You do not know how funny I find it that you bring up 1980 and Ronald Reagan as a less partisan time in American Politics.
I suppose you have a point, but it's still an odd thing to hear; because having lived through it, it was one of the time when ideology became a major factor in voting. Reagan was what passed for an extreme Right Wing Candidate at the time. He had run for president several times and was considered too conservative to win a general election. He only won the GOP nomination because the Moderate more centrist republicans had imploded. First Nixon and Watergate. Then Nixon's hand appointed successor Gerald Ford, Pardoned Nixon before the 76 election. The centrists were very weakened openning the Door for Reagan. On the Democratic side, I like to call Jimmy Carter our greatest X-president for all he's accomplished out of office. He was though a pretty disastrous actual President however.
- Iranian Hostages, - Iran mocking us and Carter hiding in the rose garden of the white house trying to to upset them.. weak.
- Arab Oil Embargoes, Prices of gasoline jumped 100-200% and the nation had to go to rationing. Depending on your license plate you were limited to when you could buy gasoline at the pump. Lines for gasoline were super long, out of the parking lots and down the street from the station.
- Inflation hit 18%
- Interest rates on home mortgages were above 14%
- Unemployment under Jimmy Carter hit about 6.5% which was unusually high
I would say the Regan Democratic shift wasn't about the popularity of Reagan initially, but rather Reagan made a case that what the Democrats were doing wasn't working; which was plane to even reliable Democratic voters. That's what lead to that shift.