Missouri currently has no law that states a minimum age. Georgia, Illiniois, Maryland and Oregon are a few of the states with very specific ages. Typically 8 year olds and over can be left at home for up to several hours (usually after school before a parent gets home from work). 12 years old appears to be the most common recommendation. http://www.latchkey-kids.com/latchkey-kids-age-limits.htm provides a state by state comparison.