A Compromise to Save the Union

White Americans found compromises between slavery and freedom in the early years of the nation.

- Heather Cox Richardson

They protected slavery in the U.S. Constitution but provided for the slave trade to end in 1808. They added slave states and free states to the Union in pairs. They divided the 1803 Louisiana Purchase between slavery and freedom by letting slavery exist above the 36° 30' line of latitude only in Missouri.

But something happened in 1848 that ended the ability to compromise: The United States and Mexico negotiated an end to their recent war (1846–1848).

The Treaty of Guadalupe Hidalgo transferred a huge parcel of western land to the United States. It stretched from Texas to the West Coast, including land that would later become the states of California, Nevada, and Utah, and much of Arizona, Colorado, New Mexico, and Wyoming. The land had been a possession of either Spain or Mexico until 1848, and so it had not been included in the Missouri Compromise of 1820.