With U.S. midterm elections approaching, Russian trolls found ways to remain active on Twitter well into 2018, trying to rile up the American electorate with tweets on everything from Roseanne Barr’s firing to Donald Trump Jr.’s divorce, a Wall Street Journal analysis found.

Newly identified Russian trolls posted politically divisive messages on Twitter as recently as last month, hitting on a wide array of hot-button issues, according to a Journal analysis of recently revealed investigative documents and Twitter data.

The...