Sundown towns were once common in the North and one academic looks at the connections between such communities and voting for Donald Trump:

Did sundown towns elect Trump in Wisconsin? My research assistant, Kathryn Robinson, and I tried to find out. Since it is much easier to get county-level election returns than municipal ones, we concentrated on “sundown counties,” those having a county seat that could be established as a sundown town or likely sundown town in Loewen’s mapping. An incredible 58 of the state’s 72 counties fit into such a category. Of the 58 sundown counties 31 are 1% or less African American (and only eight more than 2%), suggesting that the proxy of the county seat works in identifying sundown areas at the county level.

The simple answer on Trump and sundown towns in Wisconsin is: “Clearly they elected him.” Sundown counties gave Trump almost 935,000 votes to Clinton’s just over 678,000. His margin in the sundown areas exceeded 256,000 votes. That Clinton won the fifteen non-sundown counties by almost 230,000 votes could not make up for Trump’s 58% to 42% margin in the sundown ones. Just short of two/thirds of all Trump voters in Wisconsin came from sundown counties. Only nine sundown counties chose Clinton with 49 for Trump…

Our appreciation of the critically important historical dimension to sundown voting—both Robinson and I are trained in that discipline—ironically came through a sociologist. That is, when I contacted Loewen to outline the project to him, he mentioned having recently been to Calhoun County, a tiny sundown county in Illinois near where I grew up. That county, he told me, had voted for Obama in the same proportions as the rest of the country in 2008. I then looked up its 2016 vote, a landslide for Trump. Robinson and I had reason to wonder if a similar swing from Obama to Trump characterized the 2008 to 2016 trajectory of sundown county voters in Wisconsin.

The pattern could hardly been more striking. In 2008, Barack Obama defeated John McCain in all but eight of Wisconsin’s sundown counties. These virtually all-white counties delivered to the African American candidate a majority of nearly 143,000 votes. The fifteen very small sundown counties discussed above supported Obama in 2008 by 57.4% to 42.6%. The countervailing continuity lay in the metro Milwaukee suburbancounties, where the vote went to the conservative candidate in both 2008 and 2016, by overwhelming margins in both cases. The intervening 2012 election proved a halfway house, with the Milwaukee suburban counties solidly for Romney but Obama splitting the other sundown counties with the Republican ticket. By 2016, just under 400,000 votes had switched from the Democratic to the Republican candidate in sundown Wisconsin. Outside of the sundown counties the pro-Republican swing from 2008 to 2016 was just 17,000 votes.

It would be worthwhile to see such research carried out elsewhere as there were more sundown towns than people imagine (even if actual laws or records about them are difficult to find).

While Loewen alerts us to this important history, it is also interesting to consider how sundown counties or towns can experience rapid racial and ethnic change. This article cites a rural community that suddenly had an influx of Latino workers for several manufacturing plants. Or, imagine some suburban areas after World War Two that had rapid development and demographic change. I’m thinking of Naperville, Illinois, a sundown town that due to high quality residential and job growth is a suburb today that is increasingly non-white and where city leaders praise the growing diversity. Is there a point where the effects of being a sundown town disappear or could such effects pop up again depending on the situation (economic factors, racial and ethnic change, certain leaders, etc.)?