Prom and graduation celebrations can often lead to under-age drinking, says Missouri law enforcement. That’s why police and highway patrol throughout the state are planning to crack down on underage drunk driving April 30 through May 13. The patrol reports from 2009 through 2011, 94 people were killed and 368 people seriously injured in crashes involving impaired drivers under 21. Missouri is a Zero Tolerance state — drivers under 21 caught with driving with even a trace of alcohol in their system lose their license.