Which side of the river is more dangerous if you're comparing St. Louis, Missouri versus East St. Louis, Illinois? It is a complicated answer and depends on exactly how you define danger.
It's like a modern wasteland. There's one Illinois place that was just ranked as the 4th most abandoned in America where more than 1 out of every 4 buildings is vacant.
If you consider yourself someone who enjoys the nightlife, you no doubt want to adventure into the cities in Illinois that never sleep. However, there are 10 that you really should avoid entering as they become extra dangerous after dark.