Book excerpt: Many theories--from the routine to the bizarre--have been offered up to explain the crime decline of the 1990s. Was it record levels of imprisonment? An abatement of the crack cocaine epidemic? More police using better tactics? Or even the effects of legalized abortion? And what can we expect from crime rates in the future? Franklin E. Zimring here takes on the experts, and counters with the first in-depth portrait of the decline and its true significance. The major lesson from the 1990s is that relatively superficial changes in the character of urban life can be associated with up to 75% drops in the crime rate. Crime can drop even if there is no major change in the population, the economy or the schools. Offering the most reliable data available, Zimring documents the decline as the longest and largest since World War II. It ranges across both violent and non-violent offenses, all regions, and every demographic. All Americans, whether they live in cities or suburbs, whether rich or poor, are safer today. Casting a critical and unerring eye on current explanations, this book demonstrates that both long-standing theories of crime prevention and recently generated theories fall far short of explaining the 1990s drop. A careful study of Canadian crime trends reveals that imprisonment and economic factors may not have played the role in the U.S. crime drop that many have suggested. There was no magic bullet but instead a combination of factors working in concert rather than a single cause that produced the decline. Further--and happily for future progress, it is clear that declines in the crime rate do not require fundamental social or structural changes. Smaller shifts in policy can make large differences. The significant reductions in crime rates, especially in New York, where crime dropped twice the national average, suggests that there is room for other cities to repeat this astounding success. In this definitive look at the great American crime decline, Franklin E. Zimring finds no pat answers but evidence that even lower crime rates might be in store.