In other words, being very close to hospitals and well-trained doctors (read: ones working for massive hospitals in the city) means you die less.

Doesn't mean you get hurt less, you just have faster (and some times better) care. Title is misleading.

"Perelman School of Medicine at the University of Pennsylvania and the Children's Hospital of Philadelphia (CHOP) have found that risk of death from injuries is lowest on average in urban counties compared to suburban and rural counties across the U.S."

That doesn't exactly evoke "safe", it evokes "not dying".

"...the top three causes of death were motor vehicle collisions, firearms, and poisoning."

Since when? Pretty sure heart disease and cancer should be on there.