Is DST a states rights issue in the US? What is the argument FOR keeping DST?
The argument for it kinda depends on where you are. Keeping in mind that humans are diurnal animals, take a look at this graph for your city: https://www.timeanddate.com/sun/usa/san-francisco
Here, during the winter, daylight starts between 6:23 and 7:25 in the morning. In the summer, it's between 5:47 and 7:21 am. That's with DST. Without it, full daylight would come as early as 4:47 am.
That's more dramatic if you're further north. Take a look at Minneapolis: https://www.timeanddate.com/sun/usa/minneapolis
For them, winter daylight start between 6:28 and 7:51 am. Summer daylight starts between 5:26 and 7:26 am with DST. Otherwise, it would be as early as 4:26 am.
So basically, the more north you are, the more summer daylight comes very early in the morning. Given that humans are diurnal animals, and given that a lot of jobs depend on daylight (e.g., agriculture, construction), and given that we use a social definition of time to regulate a lot of coordinated economic activity, the question is: do we adjust the schedules or the clocks?
Certainly when DST was invented, adjusting the clocks was the only practical option. If we have too many light hours in the morning and too few in the evening, let's just swap the clocks by an hour. There aren't many clocks and you get everybody to do it at once, so no communication is necessary.
These days maybe you could replace it with seasonal hours set by every business on as they see fit, but that's an awful lot of schedule-adjusting and hours-checking that needs to happen to know if you can pick up coffee on your way to work. So personally, I'm for staying with DST.
That is half the picture. The more north you are the later in the evening sunlight lasts. I grew up near Minneapolis - in winter there is nothing you can do to get daylight both before and after school hours, and when close to the equinox it is hard to even hit one if you sun during recess as well (one hour after school starts or one hour before it ends).
Daylight savings time is useless in the north because there isn't enough daylight in winter to do anything useful with no matter what you do. In summer it is pointless as there is far more daylight than you need and so you have to learn to sleep with the sun up.
Same as the argument for keeping anything else: "I'm afraid of what might happen if the system changed".
It'd be tough for New York, for example, to abolish DST without New Jersey and Connecticut doing the same, you'd have people crossing time zones part of the year in their daily commute. Then, it would be hard for New Jersey to do it without Pennsylvania (where many New Jerseyans commute to) also following suit. Likewise in New England, where Boston is the center of the universe, all of New England is best off being in sync, you don't want commuters from New Hampshire and Rhode Island to cross time zones to get to their jobs in MA.
Louisiana's legislature voted for permanent DST this year, but it's on hold waiting for federal blessing.
Where I am at right now its DST and sun up is 7am and sundown is around 7pm. Without DST it would be 6am to 6pm. I think the average person gets more use of the sun from 6pm-7pm than they do at 6-7am. A decent chunk of the population is sleeping until 7am and virtually nobody is sleeping from 6-7pm.
That doesn't really support switching away from DST in the winter. So I'd rather stay on DST all the time. But if its between never DST and DST half the year, I pick half the year.
And even if you could coordinate all that, it would have the same effect as day light savings. So why not just do it the easy way.