Final answer:
The Missouri Compromise predated Abraham Lincoln's presidency by roughly 40 years, having been enacted in 1820. Lincoln became president in 1861, facing the secession of southern states amid escalating tensions over slavery that earlier compromises couldn't quell.
Step-by-step explanation:
Before Abraham Lincoln's presidency, the nation struggled with sectional tensions stemming from the issue of slavery. The Missouri Compromise, enacted in 1820, addressed these tensions by admitting Missouri as a slave state and Maine as a free state, and banning slavery north of the 36°30' line in the remaining Louisiana Purchase territory. Decades later, Lincoln, elected in 1860, faced the secession of southern states and the onset of the Civil War, partly due to the inability to reach further compromises like the failed Crittenden Compromise, which attempted to extend the Missouri Compromise line to the Pacific.
The Missouri Compromise came well before Lincoln's term as president, with a gap of approximately 40 years separating the two events. Lincoln's term began with his inauguration on March 4, 1861, following a period of heightened tensions over slavery and territorial expansion that the Missouri Compromise and subsequent compromises failed to permanently resolve.