Don't forget metros/subways. You see a lot of luggage pass through without inspection (unlike airports or stadiums) but the potential for a terrorist attack is

Don't forget metros/subways. You see a lot of luggage pass through without inspection (unlike airports or stadiums) but the potential for a terrorist attack is real and they've been used for exactly this. So transit police in US respond very quickly to unattended packages or luggage and treat them as dangerous by default. (https://wjla.com/news/crime/suspicious-packages-in-d-c-unpackaged-54885 https://wjla.com/news/crime/suspicious-packages-in-d-c-unpac...)