Street prostitution is illegal throughout the United States. Street prostitution tends to be clustered in certain areas known for solicitation. For instance, statistics on official arrests from the Chicago Police Department from August 19, 2005, to May 1, 2007, suggest that prostitution activity is highly concentrated: nearly half of all prostitution arrests occur in a tiny one-third of one percent of all blocks in the entire city of Chicago. Street prostitutes who exchange sex for drugs are sometimes known as "strawberries".