The document discusses several key events and compromises around the issue of slavery in the United States between 1819-1854. It outlines the Missouri Compromise of 1820 which balanced the admission of slave state Missouri and free state Maine. It also discusses the annexation of Texas in 1845, the Mexican-American War from 1846-1848, and the Compromise of 1850 that included the admission of California as a free state. Rising sectional tensions over the spread of slavery led to the formation of the Republican Party and increased support for abolitionism and anti-immigrant Know Nothing movements.