Some major cities ranked by surveillance cameras per km
Not what I would have expected:
1. Seoul
2. Paris
3. Boston
4. NYC
5. Baltimore
6. San Francisco
7. Tokyo
8. London
9. Chicago
10. Philadelphia
11. Bangkok
12. Washington, D.C.
13. Milwaukee
14. Singapore
15. Seattle
16. Los Angeles
The difference here between Seoul and Los Angeles is almost 4x. Mostly I am surprised that London and also Singapore are so low. Here is the paper, via the excellent Samir Varma.