Given those terrible crimes and all the others reported every day by the national, state, and local media, it's hard to believe that crime in Ann Arbor has dropped like a rock over the last twenty-five years. But the numbers don't lie. In the four major categories tracked on the Ann Arbor Observer's monthly Crime Map--robbery, sexual assault, vehicle theft, and burglary--the number of crimes reported has fallen by an amazing 70 percent, from 2,670 in 1986 to 790 in 2010.
Robbery, sexual assault, and vehicle theft are rare enough that rates sometimes fluctuate by 30 percent or more from year to year. To iron out those oscillations, we compared rates for individual crimes based on five-year averages--1986-1990 vs. 2006-2010.
Between those two periods, violent crime was cut in half: robbery fell 52 percent, from an average 157 to seventy-five per year, and sexual assault 51 percent, from an average 131 to sixty-four per year. Property crime dropped even more: burglary by 63 percent, from an average 1,647 to 605 per year, and vehicle theft by an astounding 71 percent, from an average 526 to 155 per year--much of that due to better car lock systems.