If you've been following events in Ukraine closely, you may have seen maps, available at electoralgeography.com, showing how the ethnic Russian areas voted heavily for one candidate and the ethnic Ukrainian areas for another.
However, as the eminent historians of Eastern Europe Timothy Snyder and Anne Applebaum have written, the division is not simply based on ethnicity or language. Almost all Ukrainians can speak Russian and most can speak or at least understand the closely related Ukrainian.
The maps suggest a different story. This division of Ukraine is based, most of all, on history.
Consider the far western part of Ukraine around Lviv. In the 2010 presidential election, only about 10 percent there voted for the pro-Russia and now ousted Viktor Yanukovych.
This area was heavily Catholic and part of Poland between World War I and World War II. Before that it was in the Austria part of the Austro-Hungarian empire.
These were areas with relatively good rule of law and considerable democratic heritage. Austria instituted universal male suffrage in 1907.
Two fringe areas of western Ukraine had higher Yanukovych percentages. One is Ruthenia, part of the less democratic Hungary half of Austria-Hungary before 1918. The other was part of Romania before World War II.
Southern and eastern Ukraine, which voted between 60 and 90 percent for Yanukovych, had a starkly different heritage. Much of its land was acquired in the 18th century by Catherine the Great and was settled only in the late 19th.
Odessa on the Black Sea became Czarist Russia's great grain-exporting port in the late 19th century, with a large Jewish population later murdered in the Holocaust.
In Ukraine's far east, the city of Donetsk was founded only in 1869. Its steel industry was vastly expanded by Stalin and manned with an influx of people from the Russian countryside.
The political heritage in these areas is purely Czarist and Soviet, with little or no rule of law and just the barest smidgen -- in the last Czarist years -- of electoral democracy.
Further away from the Black Sea is north-central Ukraine and the capital of Kiev, an area that voted about 30 percent for Yanukovych. This was ruled by Russia for years, but not forever. It was part of the relatively free Kingdom of Poland from the 16th until the partition of Poland in 1772.
It seems farfetched to suppose that centuries-old events and migrations could be reflected in the election results of 2010 and the overthrow of a regime in 2014. But you can see the mark of history on current electoral politics elsewhere, in Europe and North America.