Since 1980, the U.S. prison population has grown exponentially, expanding from approximately 500,000 to 2.3 million people in just three decades. America now has the dubious distinction of leading the world in prison population: We account for 25 percent of all prisoners but only 5 percent of the global population. Our penchant for punishment has come at a cost. We spend almost $70 billion annually to place adults in prison and jails, to confine youth in detention centers, and to supervise 7.3 million individuals on probation and parole. Indeed, confinement costs have claimed an increasing share of state and local government spending. This trend has starved essential social programs -- most notably education.

Nearly 75 percent of imprisonment spending happens at the state level, where dollars are drawn from a general fund that is meant to pay for a range of public needs, including health care, housing, public assistance, and education. Whether we look back over the last two decades, or just the last two years, education, in particular, has become a casualty of state budget battles. Analysis by the National Association of State Budget Officers shows that elementary and high schools receive 73 percent of their state funding from this discretionary fund; colleges and universities count on the fund for half of their budgets. However, $9 out of every $10 that support imprisonment come from the same pot of money. With tens of billions of dollars in prison spending annually, states are finding that there is simply less discretionary money available to invest in education, especially in these lean economic times.

Indeed, as the economic downturn limited all state spending in the fiscal year 2008-2009, the share of general-fund money going to incarceration grew as expenditures in every other category -- -save public assistance -- declined. States still spend more of their general-fund dollars on education than on incarceration, but the percentage of dollars being used for incarceration is increasing, while the percentage for education is decreasing. In 33 of 50 states, corrections -- related costs made up a larger proportion of the general fund than in the previous fiscal year, while spending on K-12 and higher education decreased.

The federal stimulus, no doubt, helped states find money to pay for both prisons and other basic state services as tax revenue eroded. When future budget years arrive, however, and states and counties try to balance their books without the assistance of the federal stimulus, young people will experience more of the same: school closings, teacher layoffs, diminished after-school programs, and rising tuition at colleges and universities. All of this will happen while prison spending grows.

This tradeoff between education and incarceration is particularly acute at the community level. In many urban neighborhoods where millions of dollars are spent to lock up residents, the education infrastructure is crippled. As the prison population skyrocketed in the past three decades, researchers began to notice that high concentrations of inmates were coming from a few select neighborhoods -- primarily poor communities of color -- in major cities. These were dubbed "million -- dollar blocks" to reflect that spending on incarceration was the predominant public -- sector investment in these neighborhoods. NAACP research shows that matching zip codes to high rates of incarceration also reveals where low-performing schools, as measured by math proficiency, tend to cluster. The lowest-performing schools tend to be in the areas where incarceration rates are the highest. The following examples are instructive.

Los Angeles. California has the largest prison population in the country, with more than 170,000 individuals behind bars. In Los Angeles, more than half of current parolees live in neighborhoods that are home to less than 20 percent of the city's adult residents. More than a billion dollars are spent every year to incarcerate people from these communities. At the same time, as of spring 2010, the Los Angeles Unified School District was projecting a deficit of $640 million in the 2010-11 academic year. As a result, district officials were planning to raise class sizes and lay off thousands of teachers and other school-based staff.

How is school success affected by these policy choices and spending patterns? There is no definitive way to know what the previous spending cuts have meant for Los Angeles schools, but we do know that in Los Angeles, 67 percent of low-performing schools are in neighborhoods with the highest incarceration rates. By contrast, 68 percent of the city's high-performing schools are in neighborhoods with the lowest incarceration rates.

Philadelphia. In 2009, the School District of Philadelphia faced a projected budget shortfall of $147 million, after losing $160 million in state funding. Yet, during this same period, taxpayers spent nearly $290 million to imprison residents from just 11 Philadelphia neighborhoods, home to about one-quarter of the city's population.

As hundreds of millions of dollars are invested in incarcerating people from these select neighborhoods, the corresponding disinvestment in education in those neighborhoods is telling. Sixty-six percent of lower-performing schools are clustered in or very near neighborhoods with the highest rates of incarceration -- where the biggest taxpayer investment in imprisonment is being made. By contrast, 75 percent of Philadelphia's higher-performing schools are in neighborhoods with the lowest rates of incarceration.

Houston. In the 2009-2010 academic year, state budget cuts forced the Houston Independent School District to manage a projected $10 million shortfall. However, in the preceding year, Texas spent over $175 million to imprison residents from just 10 neighborhoods in Houston. In Houston, of the six schools deemed lower-performing, five are in neighborhoods with the highest rates of incarceration. By contrast, of the 12 schools considered higher-performing, eight are in neighborhoods with the lowest incarceration rates.

What we learn from Los Angeles, Houston, and Philadelphia is that our national priorities are misplaced, and with devastating consequences. In a few select neighborhoods, the heavy investment in incarceration over education correlates with the lowest-performing schools. These neighborhoods send more individuals to prison than to college -- reflecting the pattern of dollars invested. The relationship has not yet been shown to be causal, but we do see a correlative effect between education and incarceration. If states were to properly invest in reopening schools, keeping quality teachers, maintaining sensible classroom sizes, and sustaining the affordability of higher education, it's quite possible -- particularly for economic crimes like low-level drug dealing -- we would not need to imprison so many people and could stop sinking our valuable taxpayer dollars into an investment that has demonstrated scant return.

To shift our funding priorities, national and state policy-makers will have to choose cost-effective criminal-justice policies and focus on public-safety strategies that curb crime and reserve more of our tax dollars for our children's education. Gov. Arnold Schwarzenegger of California noted in his 2010 State of the State address: "Spending 45 percent more on prisons than universities is no way to proceed into the future. ... What does it say about any state that focuses more on prison uniforms than on caps and gowns?" Only when we make meaningful investments in schools -- not prisons -- will our nation reap the benefits through increased earnings for families, reduced unemployment, increased tax revenues from more vibrant local economies, reduced reliance on public assistance, increased civic engagement, and improved public -- safety outcomes for neighborhoods at risk of violence and victimization.