Weird thing is, people in other states that do not border 911 got emergency alerts stating the 911 system was down, then another one from the state they live in stating to ignore the previous alert as it was for Mass only.
Not sure how precisely emergency warnings can be targeted, given that in addition to mobile notifications (and cell towers can cover a large area in rural areas!) they also use channels with a larger coverage area such as TV and radio stations.
It might be unavoidable to warn some unaffected people tuned in to stations located in adjacent states due to that.
This was a cellphone notification, however, using the cellphone emergency broadcast system. It can be targeted down to the tower (although the GUI probably doesn't let you do that).
Base station coverage probably doesn't exactly match state borders though, does it?
There's a high chance at least some phone users close to state lines would have been on the "wrong" towers and accordingly not been able to reach 911 in this case.
I understand what you're trying to say, but get a map out: Maine does not border Mass, and none of our cellphone network segments touch. If I drive from Boston to Bangor (nearest major city), I will touch somewhere around 40 distinct networks during that trip ~4-5hr trip, and will have to pass through NH.
This is about 250 miles away. I assume you're west coast, this is approximately twice the distance between Seattle and Vancouver, or half the distance between SF and Seattle.
Including me.