Public buildings and structures within the United States must follow the Americans with Disabilities Act at all times, even while they are being constructed.
The Department of Justice has provided technical information for those individuals represented by the ADA. Some of those requirements are listed below, along with the link to their website.
City governments must provide doorways with widths between 32” and 48”, parking spaces at least 8’ wide so the disabled can exit and enter their vehicle with a wheelchair, minimum 5’ access aisles with curb ramps where accessible paths cross curbs, levers for door handles as opposed to knobs, and service counters no more than 36” above the floor.
You may review additional requirements set forth by the ADA by visiting their website.