History: United States Of America, 1900-1930

Crime and law enforcement
Law enforcement in the United States is primarily the responsibility of local police and sheriff's departments, with state police providing broader services. Federal agencies such as the Federal Bureau of Investigation (FBI) and the U.S. Marshals Service have specialized duties. At the federal level and in almost every state, jurisprudence operates on a common law system. State courts conduct most criminal trials; federal courts handle certain designated crimes as well as certain appeals from the state systems.
Among developed nations, the United States has above-average levels of violent crime and particularly high levels of gun violence and homicide. In 2007, there were 5.6 murders per 100,000 persons, three times the rate in neighboring Canada. The U.S. homicide rate, which decreased by 42% between 1991 and 1999, has been roughly steady since. Gun ownership rights are the subject of contentious political debate.
The United States has the highest documented incarceration rate and total prison population in the world. At the start of 2008, more than 2.3 million people were incarcerated, more than one in every 100 adults. The current rate is about seven times the 1980 figure. African American males are jailed at about six times the rate of white males and three times the rate of Hispanic males. In 2006, the U.S. incarceration rate was over three times the figure in Poland, the Organisation for Economic Co-operation and Development (OECD) country with the next highest rate. The country's high rate of incarceration is largely due to sentencing and drug policies.