Before President George H. W. Bush signed into law the Americans with Disabilities Act on July 26, 1990, many people couldn’t navigate their homes and their communities. There simply weren’t enough ramps for wheelchairs or sign language interpreters or flexibility in jobs to accommodate physical and mental challenges. “It’s not the disability that’s the problem, it’s the environment and the attitudes,” said Patricia Yeager, CEO of The Independence Center, which on Thursday hosted a virtual celebration in honor of the 31st anniversary of the ADA’s birth. “That systemic setup kept us from participating.” The act, which prevents discrimination in employment, transportation, public accommodations, communications and access to government programs, culminated decades of work of disabled communities rising up to demand full participation in society, speakers said.