I'm new here, so probably most of y'all already know this, but the U. S. Parks Service issues by mail an "Access Pass," that will allow you to use Segway-like devices in many places the general public cannot. They will also get you in free, which could be a big deal, now that the current administration wants to charge as much as $70 for admission to the most popular parks.
The passes are "available to U.S. citizens or permanent residents of the United States that have been medically determined to have a permanent disability (does not have to be a 100% disability) - that provides admittance to more than 2,000 recreation sites managed by five Federal agencies."
Details and the application can be found here:
https://store.usgs.gov/access-pass