I believe it became common because as civilizations grew from food abundance and population growth, the civilizations wealth in how they produced it, usually by trade in food needed to be contained. So economic specialization was needed so that their prosperity could be controlled.
The Supreme Court ruled that states cannot regulate interstate railroads.
Cities couldn't thrive in the harsh winter of New England but villages could work together to protect each other against it.
There are many ways to study, but there are apps where you work for 40 minutes and get like a 10 minute break. There’s also Khan Academy which gives you sample problems and Quizlet has flash cards and games to help you remember. You can also reach out to your teacher for any study tips.
