The war was extensively supported in the southern states but opposed in the northern states. This division largely developed from expectations of how the expansion of the United States would affect the issue of slavery. At the time, Texas recognized the institution of slavery, but Mexico did not. Many Northern abolitionists viewed the war as an attempt by the slave-owners to expand slavery and secure their continued influence in the federal government. Henry David Thoreau wrote his essay Civil Disobedience and refused to pay taxes because of this war. The main issue that encouraged sectionalism was the expansion of slavery into the national territories. The Missouri Compromise of 1820 banned slavery in national territories north of 36 degrees.