mar 3, 1820 - Missouri Compromise
Mar 3 1820, states' rights issue
Agreement where Missouri was admitted as slave state and Maine as free state to keep Congress in balance. A line for slave and free states went along the 36°30' parallel. All states under that were allowed to have slaves and those ones above that weren't.
Added to timeline:
Timeline: Causes of the American Civil war by Veera Rakkolainen