49.30  All candidates and issues on one ballot — exceptions.
  All constitutional amendments, all public measures, and the names of all candidates, other than presidential electors, to be voted for in each election precinct, shall be printed on one ballot, except that separate ballots are authorized when it is not possible to include all offices and public measures on a single ballot. In the event that it is not possible to include all offices and public measures on a single ballot, separate ballots may be provided for nonpartisan offices, judges, or public measures.
[C51, §256; R60, §491; C73, §616; C97, §1106; S13, §1106; C24, 27, 31, 35, 39, §748; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §49.30]
90 Acts, ch 1238, §17; 94 Acts, ch 1169, §64; 97 Acts, ch 170, §29; 98 Acts, ch 1100, §6; 2002 Acts, ch 1134, §31, 115; 2005 Acts, ch 152, §7, 8; 2007 Acts, ch 190, §20 – 22; 2010 Acts, ch 1033, §18

See also, §49.43, 52.24