Daylight saving time which started at 2:00 AM Sunday, every place in the USA except Arizona, lasts about 7.5 months. Standard time lasts about 4.5 months. So, clearly, we should rename daylight saving time as standard time, and find a different name for the other 4.5 months.
If you want to be pedantic, and I frequently do, you’re right. In Arizona, the Navajo nation does observe daylight saving time, even though the rest of the state doesn’t. I do know that, but I don’t know why.
And, please, stop saying we gain an hour of daylight. We do not! Daylight saving time is a ruse to fool you into getting up an hour earlier in the morning when it’s in effect.