I was just looking at county maps for the 1988 election, and Cameron Parish-which was Trump's best parish in Louisiana last year and gave him nearly 91% of the vote-actually voted for Dukakis that year! In fact, Dukakis won a substantial block of Cajun-influenced parishes in the southwestern part of the state, most of which went for Trump by landslide margins in 2020. Conversely, LaSalle Parish gave H.W. Bush more than 70% of the vote and was his best parish in the state. Cameron and LaSalle were far apart in 1988, but close together in 2020. Moreover, Biden carried Caddo and East Baton Rouge Parishes, both of which had gone to Bush. There have been substantial coalition changes at the county level in 32 years, although Orleans Parish was and remains a Democratic stronghold.
The Catholic areas used to be among the most Democratic in the state, as was most evident in the Northern Ireland-tier sectarian 1960 election: Catholics for Kennedy, Protestants in heavily white areas for Nixon, Protestants in racially mixed areas for the unpledged electors. In 1964, the most Catholic areas swung a lot less towards Goldwater than the rest of the state. In the 90s, Acadiana was stronger for Perot than much of the Deep South, foreshadowing movement away from the Democratic brand in the 21st century.