The Iowa Constitution of 1857, which is still in effect today, states that counties must have an area of at least 432 square miles (1,120 km2), and no county may be reduced below that size by boundary changes.
1857年的《爱荷华州宪法》至今仍然有效，它规定县的面积至少为432平方英里（1120平方公里），任何一个县不得因边界变化而缩小到这个规模以下。