This graphic shows just how widespread meth is in the United States

Flickr/Myfuture.com

Nearly half of all inmates in US federal prisons are serving sentences for drug offenses.

But exactly which drugs are getting people locked up?

In more than half of the 50 states, it's meth. According to research from the United States Sentencing Commission, methamphetamine produced more offenses than any other drug in 27 states, including much of the West, Midwest and the South.

DrugAbuse.com put together a graphic using data from the sentencing commission:

DrugAbuse.com

Heroin produced the most drug offenses in 10 states, while powder cocaine produced the most or tied for the most in seven, including Washington, D.C.

Marijuana may be the most widely used illicit substance in the country, but it was responsible for the most drug offenses in just four states.Twenty-five states and D.C. have laws legalizing marijuana in some form.

Here's the breakdown of drug offenses state by state:

DrugAbuse.com

The graphic illustrates just how pervasive meth has become in some states. In Hawaii and Montana, meth was responsible for more than 90% of all drug offenses. And in North Dakota, Wyoming and Idaho, the figure topped 70%.

Meanwhile, Arizona stands out for its disproportionately high rate of marijuana sentences. The state has arguably the toughest marijuana penalties in the country — possessing any amount of the drug under two pounds can carry a sentence of up to two years.