142nd Regiment, Illinois Infantry (100 days, 1864)
The 142nd Regiment, Illinois Infantry (100 days, 1864) was organized at Freeport, Illinois, and mustered in for 100 days June 18, 1864. It mustered out October 27, 1864. 
For more information on the history of this unit, see:
- The Civil War Archive section, 142nd Regiment Infantry, (accessed 15 June 2012)
- The Wikipedia article, 142nd Illinois Volunteer Infantry Regiment, (accessed 15 June 2012)
Companies in this Regiment with County of Origin
Men often enlisted in a company recruited in the counties where they lived though not always. After many battles, companies might be combined because so many men were killed or wounded. However if you are unsure which company your ancestor was in, try the company recruited in his county first.
The following counties of origin are taken from the Adjutant General's Report, found on the Illinois Civil War Rosters web site. Roster pages are from the same report found on the Internet Archives web site. The rosters show the men who served in each regiment, their residences, dates of enlistment and mustering out, and other remarks.
- Civil War Soldiers and Sailors System, (accessed 30 Dec. 2010) can be searched by soldier's name or by regiment; includes regimental rosters and additional history of the regiment.
- National Park Service, The Civil War Soldiers and Sailors System (accessed 4 January 2011).