The count of 40,000 Missourians serving the South was derived by the Yankees...The actual figure will never be known but it was actually nearer 80,000. Furthermore many of the Yanks 110,000 consisted of Missouri Southerners who were forced to join the EMM "Paw Paw" Militia in order to stay near home and protect their families, some of these men were former Confederate (or MSG) soldiers who had taken "The Oath".
Many of those 110,000 Union soldiers were not even citizens of Missouri.
Using my home county (Monroe) as an example, an 1862 edition of the local newspaper, The Paris Mercury, stated that as of that date more than 1500 boys from Monroe County were off fighting for the South....this in a county with pop of abt 9500 including abt 2500 slaves...Missouri has 114 counties, do the math..