San Bernardino is a relatively large city with diverse neighborhoods, meaning safety can vary from one area to another. It has had struggles with crime in the past, so as a solo female traveler, it would be crucial to stay alert and maintain a high level of caution especially during the evening hours. Always research specific neighborhoods before visiting, use well-populated and well-lit streets, and make use of reliable transportation options. The destinations frequently visited by tourists are generally secure and authorities are typically present in those areas.