Around half of people who are imprisoned in the U.S. had no earnings in the years leading up to their incarceration — and the year before the percentage jumps to 80%, according to a new study by the Brookings Institution which examined IRS filings and the BJS National Prisoner Survey.

Expand chart Data: Brookings Institution; Chart: Chris Canipe/Axios

Why it matters: The U.S. has the highest imprisonment rates in the world — and a quarter of formerly incarcerated Americans will end up back in prison within 8 years of their release, often due to the difficulty in making a living with a criminal record. Joblessness and poverty not only characterize the life of former prisoners, but also the life of those who will end up in prison,

One stark statistic: Three years before being incarcerated, less than half of prime-age men are employed, and of those employed, only 13% earned more than $15,000 — with a median earning of $6,250.

Other notables:

About one third of all 30-year-old men without work — and about half of those from below-median income families — are either in prison or are unemployed former prisoners, the study found.

of all 30-year-old men without work — and about half of those from below-median income families — are either in prison or are unemployed former prisoners, the study found. Girls from families in the lowest 10% for family income are almost 17 times more likely to be incarcerated than those from the top 10%. For boys, that disparity jumps to a factor of 20.

for family income are almost 17 times more likely to be incarcerated than those from the top 10%. For boys, that disparity jumps to a factor of 20. Men growing up in single-parent families in the in the bottom 30% for family income make up almost half of the male prison population.

in the in the bottom 30% for family income make up almost half of the male prison population. The Brookings study looked at neighborhoods with the highest and lowest incarceration rates. Neighborhoods that were predominately black, had high child poverty rates and high male unemployment rates characterized the top neighborhoods for incarceration. And white, affluent zip codes made up the neighborhoods with the lowest incarceration rates.

with the highest and lowest incarceration rates. Neighborhoods that were predominately black, had high child poverty rates and high male unemployment rates characterized the top neighborhoods for incarceration. And white, affluent zip codes made up the neighborhoods with the lowest incarceration rates. The jump in no earnings the year before incarceration is most likely linked to criminal activity and jail time before trial or sentencing.

Go deeper: The puzzle of getting former convicts into jobs.