“If you build it, they will come.” This famous line from “Field of Dreams” concerned the turning of a cornfield into a ballpark, but it could also apply to American prisons.

The United States has built many new prisons since the 1970s, and inmates have come into them beyond capacity, creating many problems for our prisons as well as for our society. If baseball is the “great American pastime,” then mass incarceration is the “great American folly.”

To fight crime, the United States began a “get tough” or “mass incarceration” approach in the 1970s that involved longer prison terms and many more life sentences, mandatory minimum penalties for drug offenses and other crimes, and the ending of parole in many states. This approach led imprisonment to surge. In 1972, the U.S. had 196,000 prisoners, while today it has 1.6 million prisoners despite a slight recent decline. During the past four decades, then, the number of prisoners has risen by an astounding 700 percent.

In addition to these prison inmates, we also have about 700,000 jail inmates, for a total of about 2.3 million Americans behind bars at any one time, equal to a rate of one for every 100 adults. This rate is the highest in the world and about eight times higher than the average rate for all other democracies.

Another 4.8 million people are on probation or parole. All these figures yield a total of about 7 million Americans, or 3 of every 100 adults, under correctional supervision of some kind. As you might suspect, our corrections system is thus very costly. In fact, it costs taxpayers more than $83 billion annually.

This huge expenditure might make sense if mass incarceration significantly reduced the crime rate. However, most criminologists agree that mass incarceration reduces criminal behavior by only a very small amount and does so at a very high cost.

For example, several studies find that a 10 percent rise in the imprisonment rate produces a decrease in the crime rate of no more than 4 percent and perhaps as low as 1 percent. Using the latter figure, the U.S. would have to imprison 160,000 more offenders (10 percent of the 1.6 million current prisoners) to reduce the crime rate by 1 percent. At a national average cost of about $32,000 to house each prisoner, these new prisoners would cost more than $5 billion annually, and the building of new prisons to house them would cost billions of dollars more, all to achieve a mere 1 percent decrease in crime.

Any business that spent so much to achieve so little would soon be closing its doors.

Mass incarceration has also produced other problems, which criminologists call “collateral consequences.” First, its huge cost takes needed dollars away from other pursuits, including aid for higher education and programs that help poor families.

Second, 7 million children have had a parent in prison, putting them at greater risk for psychological problems and poor school performance.

Third, because so many inmates are behind bars, and most are eventually released, some 700,000 prisoners re-enter their communities every year, where they have bleak prospects for employment and stable relationships and often commit new crimes. Most prisoners come from disadvantaged communities, but mass incarceration ironically worsens their communities.

Fourth, mass incarceration has had a huge racial impact. As the U.S. cracked down on crime and drugs, African Americans and Latinos were imprisoned out of proportion to their actual involvement in crime and use of illegal drugs. Today about one of every three young African American males is under correctional supervision, and hundreds of thousands of African Americans have lost their right to vote because of their prison records.

Roughly half of all prisoners are incarcerated for nonviolent offenses: property crimes and drug offenses. The Center for Economic and Policy Research in Washington, D.C., concludes that the number of these nonviolent offenders could be halved without endangering public safety, at a savings of $17 billion annually. These savings could be used to address budget deficits at the state and federal levels and to fund programs, such as early childhood visitation to families with children at risk for delinquency and other problems, that are far more cost-effective than incarceration in reducing crime.

This reduction in nonviolent offenders is just one of many measures that criminologists recommend to reduce the number of people behind bars and to save billions of dollars annually. Adoption of these measures would help greatly to reduce the harm caused by the “great American folly” of mass incarceration.

Steven E. Barkan is a professor of sociology at the University of Maine and a past president of the Society for the Study of Social Problems. He is a member of the Maine chapter of the national Scholars Strategy Network, which brings together scholars across the country to address public challenges and their policy implications. Members’ columns appear in the BDN every other week.