Vernon County, Missouri

Vernon County, Missouri sits along the Kansas border of the state, close to the southwest corner.  The original inhabitants were the Osage, and one can visit the Osage Village State Historic Park, where, in the 1700s, there were between 2,000 and 3,000 people living in harmony.  They were both farmers and hunters, and were well known for their horsemanship.  In treaties, the Osage signed away their land rights, and were moved to a reservation in Oklahoma. 
   Vernon County comprises 837 square miles, of which 10 square miles are water.  There are three main rivers, the Marmaton, Osage and Little Osage; these are fed by 35 creeks, branches, and rings. Vernon County itself  was founded in 1855, and was named after an American Officer who fought at the Battle of New Orleans.  The town of Nevada (the first a is long) is the county seat.  My father's grandparents and great-grandparents settled there in 1854 and 1855.
    Vernon County suffered considerable damage during the Civil War.  The courthouse was burned by Union Amy soldiers on 23 May 1863, along with the entire town of Nevada.  (The present courthouse dates to 1907.)  Vernon County was one of four Missouri counties that were completely depopulated by Union General Thomas Ewing's notorious General Order Number 11 in 1863.  Most of the people who lived in the county were not allowed to return to their homes and farms until after the end of the Civil War in May 1865.
   My Dad's maternal people moved to Vernon County from Kentucky and Tennessee, and they were, mostly, farmers.  My Dad's paternal people were farmers who spread from Maine and Massachusetts, across New York and on to the Ohio Valley.  A lot stayed in Indiana, while others moved on to Iowa.  From Iowa, they, mostly, moved to Kansas, while some went on to Oregon, Washington, and down to California.  Dad's folks stayed in Kansas, then went to Oklahoma, back to Kansas, and finally, over to Howell County, Missouri - east of where Dad's Mother grew up, in Vernon County.
    My fourth-great-grandfather, Reuben Nock, lived near my other fourth-great-grandfather, Hatevil Hall in Maine.  They both had large families.  Two Nock sons married two Hall daughters, and two Hall sons married two Nock daughters.  So there were four families that were double-first-cousins.  It's the grandchildren of those double-first-cousins of the Hall/Nock crosses that have me wondering... 
   Why did several of those families end up living in Vernon County, Nevada between 1880 and 1920?  Were they frequent letter writers, who loved the area, and enjoined others of the far-flung family to move there?  Some of the men were harness makers, others were teamsters, others were farmers, and a few were merchants....  But why Vernon County?  Maybe I need to go spend several days there, instead of the few hours I've had...  Is a puzzlement!