You can check safety data in NY and SF at www.NabeWise.com I would imagine government sites and police reports can give a picture of what you are looking to get answered, but the safest place overall is probably the place with lowest population. I don't think that's the answer you are looking for. Maybe narrow your question a bit to include population data, time period, or another variable.
I would think somewhere like Sunshine, WY would be a very safe place to live.
I would say a place with a lot of families like oklahoma or pheonix, AZ or indianapolis