Missouri Counties during the Civil War

Recently I was reading excerpts from William Monks's book entitled A History of Southern Missouri and Northern Arkansas, and I was struck by an observation the author made about the differing political makeup of Howell County, where he lived, and that of neighboring Oregon County. Monks was a former Union officer who had made a name for himself fighting Confederate bushwhackers during the war. After the war, he went home to West Plains. Although his family and those of many other Union men had been forced out of Howell County during the war, Union sentiment soon dominated in the county once they returned. Not so in neighboring Oregon County, where lawless bands under former Confederate guerrillas like Dick Kitchen and Jim Jamison held sway. Monks was called upon by Missouri Governor Thomas Fletcher to help eradicate the lawless bands from Oregon County.
What struck me as interesting was the fact that two adjoining counties could be dominated by such diametrically opposed political sentiments. During the Civil War, the state of Missouri was very divided, but generally speaking Union sentiment dominated in the urban areas (especially St. Louis), while Confederate sympathies were more prominent in the rural areas. The general rule, though, did not always apply. For instance, in the southwest corner of the state (the part of Missouri I am most familiar with), Vernon County was about as Southern in sentiment as a county could be. Yet, Cedar County, right next door to the east, tended to be dominated by Union sentiment. This clash in sentiment between neighboring counties led indirectly to the murder of Augustus Baker by John Frizzell in May of 1863 and more directly to the subsequent burning of Nevada later the same month.