The United States has the world's largest prison population, with more than two million behind bars. Civil rights lawyer Michelle Alexander says this is mainly due to the American government's "war on drugs," launched in 1982 under President Ronald Reagan. In 2010's The New Jim Crow, Alexander explains how this government initiative led to America's black citizens being imprisoned on a colossal scale. She compares this mass detention-with black men up to 50 times more likely to be jailed than white men-to the Jim Crow segregation that dominated the American South between 1877 and the 1960s. Though the Civil Rights Movement supposedly ended segregation in the early 1960s, the war on drugs opened the door to a new racial caste system. Alexander also argues that modern segregation doesn't stop once blacks leave jail either, with drug offenders finding it tough to gain meaningful employment and housing. She says this phenomenon has hardly been noticed, because America has proclaimed itself a "colorblind society."