There is a stunning gap between the number of white and black inmates in America's prisons

John Moore/Getty ImagesA new study shows a large disparity between imprisonment rates for African-Americans, whites and Hispanics.

The study, published by The Sentencing Project, a nonprofit that advocates for criminal justice reform, looked at incarceration rates for ethnic groups in every state using data from the Bureau of Justice Statistics.

Here are some of the most striking finds:

• In state prisons, African-Americans are incarcerated at 5.1 times the rate of whites.
• Five states - Iowa, Minnesota, New Jersey, Vermont, and Wisconsin - have a disparity of more than 10 to 1.

• Twelve states have prison populations that were more than half black: Alabama, Delaware, Georgia, Illinois, Louisiana, Maryland, Michigan, Mississippi, New Jersey, North Carolina, South Carolina, and Virginia.
• Maryland has a prison population that's 72 percent black.

• In eleven states, at least 1 in 20 adult African-American males is in prison. In Oklahoma, it's 1 in 15.

• Latinos are incarcerated at 1.4 times the rate of whites.
• Disparities between imprisonment rates for Hispanics and whites are particularly high in Massachusetts (4.3:1), Connecticut (3.9:1), Pennsylvania (3.3:1), and New York (3.1:1)

The study cites three major reasons for the disparity: policies and practices such as harsh sentences for drug-related crimes that disproportionately affect African-Americans, implicit racial biases that affect judges, and structural disadvantages that impact African-Americans before they enter the criminal justice system.

"For a society that considers itself to be fair and just and hold these values...it forces us to question whether we're really abiding by that value system," said Ashley Nellis, the author of the study. "There's definitely a growing concern about our system of mass incarceration in the USA."

The research comes as the U.S. is embroiled in controversy over racism in police forces following the deaths of several unarmed African-American men. Nellis believes that the ultimate disparity in imprisonment rates of different races can be traced all the way through the criminal justice process.

The study outlines a number of possible reforms, including efforts already made by some states to reduce prison populations by shortening sentences for drug-related crimes and training judges on how to avoid implicit biases.

"Regardless of how we got to the system we're in, it's imbalanced," Nellis said. "And it's affecting African-American families and communities."