The NAACP has been saying it for decades. A few years ago, Newt Gingrich realized it was true. The ACLU has filed lawsuits to end it. President Barack Obama and Attorney General Eric Holder are beginning to understand it. Texas Governor Rick Perry, Pennsylvania Governor Tom Corbett and Louisiana Governor Bobby Jindal are all on board.

What realization could possibly inspire consensus from such diverse voices? It is the understanding of the horrors of mass incarceration.

One in 100 adults in the U.S. lives behind bars. One in nine African-American men are imprisoned. This country’s addiction to incarceration has not made us safer, but has instead imposed upon us an untenable, senseless tax while unfairly targeting poor communities of color and perpetuating crime and violence in our neighborhoods. Lawmakers on both sides of the aisle and activists on the left and the right are taking action to roll back imprisonment rates.

So why, then, is Chicago Mayor Rahm Emanuel lobbying the Illinois legislature to funnel more people into prison for longer? During the recent veto session last week, Emanuel requested that the legislature impose a mandatory three-year prison term on people who are convicted for the unlawful possession of a firearm.

Thankfully, the proposal failed, when Representative Ken Dunkin (D-5th) wisely requested information about the fiscal impact of the mandatory minimums. The analysis wasn’t completed by the time the legislature adjourned, but had it been finished, it would have revealed a staggering price tag. The Illinois Sentencing Policy Advisory Council estimated (PDF) that the cost of the Mayor Emmanuel’s proposal could exceed $965 million a year.

Chicago’s communities have been ravaged by mass imprisonment. The U.S. currently has the dubious distinction of having the highest per capita incarceration rate in the world. And communities on Chicago’s West and South sides have incarceration rates that are double—and sometimes triple—the national average.

This is not because more crime occurs in these neighborhoods. A National Institute of Health study that focused on the effects of mass incarceration on Chicago’s neighborhoods found that communities marked by poverty and racial segregation experience incarceration rates that are more than three times higher communities with similar crime rates. The same study also found that “the combination of poverty, unemployment, family disruption, and racial isolation is bound up with high levels of incarceration even when adjusting for the rate of crime that a community experiences. These factors suggest a self-reinforcing cycle that keeps some communities trapped in a negative feedback loop.”

Seventy percent of people in Illinois prisons are there for nonviolent offenses that in a more effective and cost-efficient system would be handled through community-based sanctions. Imprisonment frays community and family connections, interrupts employment and education, and is a deeply dehumanizing and traumatic experience. People returning home from prison struggle to reconnect with their families, find work and adhere to burdensome parole conditions. More than 50 percent of people who are formerly incarcerated in Illinois return to prison within three years of their release.

So by targeting neighborhoods for mass imprisonment, law enforcement officials have created a well-greased revolving door between prisons and our communities. And in so doing, they have destroyed the only things that have ever been proven to create safe neighborhoods. Emmanuel’s mandatory minimum proposal would only serve to fan the flames of Chicago’s failed prison and policing initiatives. Thousands of young, mostly African-American men would be funneled into already overcrowded prisons.

Once there, they will languish behind bars—denied access to even the most basic educational programs which have been defunded because of budget shortfalls. Many will endure the brutal violence and sexual assaults that are endemic in a prison environment. Most will spend their three years behind bars in forced idleness. This is the case not only in Chicago, but across the country.

Many will enter prison without any gang associations—but a recent survey of Corrections Commissioners found that more than half of all people behind bars became affiliated with a gang only after entering prison—often because gang affiliations offer some protection from prison violence.

And of course, the imprisonment of these men will leave deeps void in their communities: more children will be forced to visit their fathers behind bars, mothers will lose their sons, families will struggle to put food on the table because of lost income. After living for three years in violent, over-crowded prisons, after watching helplessly as their families struggle without them, these young men will return to our neighborhoods. And what will they find when they return?

They will find communities where the Emmanuel has shuttered schools and mental health centers in an effort to save taxpayer dollars. It is a sad irony that this same mayor who cried budget woes while refusing to fund community mental health services and closing 54 schools is now demanding than Illinois taxpayers pay more than $1 billion over the next 10 years for prison cells.

Expecting our prison system to end (or even curb) violence in our communities is like expecting fast food giants to end the obesity epidemic. Fast food restaurants may tout their sparse healthier options, but in the end, they can only turn a profit by getting us hooked on food that is bad for us. Prisons may incapacitate some people for a relatively short period of time, but in the long run, imprisonment serves only to destabilize communities and create the very conditions that perpetuate violence.

The Chicago mayor and his allies vow to bring mandatory minimums back before the legislature. Elected officials in any city who care about violence on our streets must reject any proposal that will contribute to the negative cycle of imprisonment. Reducing crime on the streets is not about locking up more people for longer.

It is about providing opportunities for people outside the prison walls in Chicago and every other American city.