How do I know if US lettuce is safe, given the E. coli outbreak?
The CDC's current advice as of April 20 2018 is quite simple:


  Do not buy or eat romaine lettuce at a grocery store or restaurant unless you can confirm it is not from the Yuma, Arizona, growing region.


So, by the CDC's definition of safety, it's not safe if it's romaine possibly from the Yuma area. It has nothing to do with where you are; things get shipped all around.