Final answer:
The split of the Louisiana Territory at 36° 30' north latitude was caused by the Missouri Compromise of 1820, which sought to maintain a balance between slave and free states and provided a temporary resolution to the growing sectional conflict over slavery.
Step-by-step explanation:
The Louisiana Territory split at 36 degrees 30 minutes north latitude was caused by the Missouri Compromise. The compromise, largely negotiated by Henry Clay, was designed to balance the power between slave and non-slave states.
It allowed Maine to enter the Union as a free state and Missouri as a slave state. The compromise drew a line at Missouri's southern border, latitude 36° 30', marking a new dividing line for slavery across the Louisiana Purchase.
Slavery was permitted south of this line, but was prohibited north of it, except for Missouri itself. The Missouri Compromise was seen as a temporary solution to the growing sectional conflict over slavery.
It would eventually be considered a contributing factor to tensions leading up to the Civil War. Thomas Jefferson, witnessing the events, expressed concern that the compromise might deepen the division on the issue of slavery, forewarning of potential disunion.