I just read the Wikipedia article on the 1999-2006 Irish-American mayor of Baltimore, who became governor in 2007 (as did Carcetti, the Italian-American mayor in the series, played by an Irish actor who couldn't completely conceal his accent). Like Carcetti, he was a young reformer who tried to improve the police department and reduce the crime rate. The article gives some crime statistics that appear to confirm the level of violence portrayed in The Wire. The city was fifth most dangerous in 2005 and twelfth most dangerous in 2006. The overall rate of violent crimes dropped by 14% from 2000 to 2003 (The Wire first aired in June of 2002), but the murder rate increased slightly, peaking at 276 in 2004, and still five times as high per capita as New York City in 2005.