Did you lock your doors in the US?

I locked my doors everywhere except for NH where we had no locks, in a dorm type situation and in a small town in Rhode Island.

And then we all went to see House of a 1,000 Corpses and FREAKED and got some locks.

Grew up in smalltown/rural Kansas (middle of nowhere!), and you bet we locked our doors at night & when we left the house!  Not when we were at home during the day however.

This happened about a 3 hour drive away from where we lived, about 6 years before I was born & people remembered it -- Truman Capote's In Cold Blood was based on it.

We didn't have anything worth stealing, however, and in her later years - my mom (by then living there alone) was infamous for locking herself out of the house as her wits started leaving her... Which meant friends & neighbours got to be topnotch at helping her break into her own house, and one time she just bashed in a window with her cane & ending up badly cutting herself on the broken glass.  

Whenever I've lived in cities, I always locked my doors - here or there.  And I keep my front door locked here (we live on a high street) but if I'm on the ground floor & the weather's pleasant, I often leave the door to the back garden propped open, otherwise it's locked.

And then we all went to see House of a 1,000 Corpses and FREAKED and got some locks.

  I forgot about that movie.

I've just been informed that we don't lock our doors at night. 

Always. I have lived multiple places in the U.S and we've always locked our doors and had an alarm system. In New York it's rather odd to hear (at least for me) of someone not locking their doors, my aunt doesn't and she and her husband got robbed. Yet they still do not lock them. I just cannot imagine leaving my house, with or without people inside, and not turning to lock the door. The idea is just odd to me.

Oh, I never locked the door if someone was at home, unless they were asleep or in the shower or something.

I grew up in rural SW PA and not only did we never lock the doors even when not at home, we left the car keys on the dashboard!

This continues even till today and in the 30+ years my mother has lived there, she has never had a problem.

When I first moved to CA at age 18, I was forever being told off by my flatmates for forgetting to lock the front door.

We live on acreage on an island with low population (in the US) and we lock our doors at night. I suppose it's out of habit, or maybe partly that and partly worrying something will happen. I've always locked my doors, but I haven't always locked my car doors. When we lived in Oregon and I watched my neighbor's car and garage (they often times forgot to close their garage) get snooped through at 2am I realized how important it is to remember to lock. (Side story, I called the police, the police came and picked up the guy, they then wanted me to id him, I did and a year to the day later he came back and egged our house  .)
I don't think I will ever live anywhere that I don't lock things up- at least at night.