01/18/2026
The Missouri Compromise Line was drawn up in 1820 to prohibit slavery in territories north of said line, (except Missouri). But the Mexican-American War of 1846-48 and the conquest of California, New Mexico, Arizona, and Texas caused an escalating series of crises over the course of the 1850s, culminating in the Civil War. The first was caused when California entered the Union as a free state, with southern California crossing the line but still prohibiting slavery. Consensus over the line, and slavery, failed, but various ad hoc compromises would keep the union intact until 1861 and Confederates firing on Fort Sumpter.
