https://www.nps.gov/arch/learn/management/segway.htm
In CA, I went to Angel Island State Park. I called to ask if I was allowed. The park superintendent asked that I get a note from my doctor.
On his letterhead, it simply said, "I am the attending neurologist for (insert name). He uses a Segway as his mobility device."
No issues at all.
https://www.flickr.com/photos/davis_...57644075368781