Yes you can
Yes.water is acceptable, no Gatorade or soda
Yes.
Yes. I actually carried a back pack with me everywhere we went. They check it at each place and you have unzip every compartment, but it was worth it to get to carry every we needed for long days out.
Yes you can bring water
Yes we were able to bring in water bottles to all the Smithsonian museums
Some places you can and some not. You can have the empty bottles and refill. There are a lot of water fountains everywhere. The capital tours for sure No Food or Drink. Not even in packed containers. We had to throw out our candy bars.
Yeah but not soda
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