Boston did a pretty good job, back before the crackdown started, I lived in an area where the park I walked through to get home was nicknamed "muggers' park". You would hear someone yell they'd been stabbed (almost nightly) or a gunshot from outside your apt. window, dial 911 and get a busy signal! Then they added beat cops, and there was a no-stopping rule in the park, if you sat down anywhere, the police would tell you to move along, but it worked, and their presence was welcome by most everyone in the hood. The citizens also organized neighborhood watches with the mayor and the police' help. I give them (Mayor Menino, and the police) a lot of credit, as well as the local neighborhood citizens! You have to work together.

Hi sahara, I visited Boston last year and was very comfortable to be there. Strange towns or cities can be daunting to the visitor but there were a lot of police in evidence, more so than in London say, where they just appear to whizz around in cars with lights flashing and horns blaring.
In my home town the sight of a policeman on the beat is so unusual that people remark on the fact.