<page_title> Marshall County, Illinois </page_title> <section_title> Demographics </section_title> <table> <cell> 2010 <col_header> Historical population </col_header> <col_header> Census </col_header> </cell> <cell> 12,640 <col_header> Historical population </col_header> <col_header> Pop. </col_header> </cell> <cell> U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2013 <col_header> Historical population </col_header> <col_header> Census </col_header> <col_header> Pop. </col_header> <col_header>  </col_header> <col_header> %± </col_header> </cell> </table>
As of the 2010 United States Census, there were 12,640 people residing in the Marshall County.