(CNN) During a campaign event in Nashua, New Hampshire on Tuesday, Democratic presidential frontrunner Joe Biden was asked about the 1994 crime bill he helped write as a Senator from Delaware. The question posed to Biden concerned the impact the bill had on mass incarceration rates, particularly among minority communities living in poverty, and what he might do to alleviate those effects.

"Folks, let's get something straight," Biden replied before defending the 1994 crime bill. "This idea that the crime bill generated mass incarceration—it did not generate mass incarceration."

Facts first: Following passage of the 1994 crime bill, incarceration rates in the US continued to rise for more than a decade. Experts however say it's hard to determine how much of this increase came as a result of the 1994 bill, since incarceration rates had been steadily rising since the early 1970s.

From 1973 to 2009, the incarceration rate in the US more than quadrupled, from 161 people to 767 per 100,000 nationwide, according to a study by the National Research Council. It's hard to pin that trend on one particular piece of legislation.

"No one bill created mass incarceration," Wanda Bertram, communications strategist at the Prison Policy Initiative said Tuesday, noting that the 1994 crime bill was one part of the overall "tough on crime" movement that contributed to the four decade rise in the US prison population.

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