When Colorado expanded Medicaid coverage under former President Barack Obama’s health care law, the largest provider in the Denver region hired more than 250 employees and built a $27 million primary care clinic and two new school-based clinics. Emergency rooms visits stayed flat as Denver Health Medical Center directed many of the nearly 80,000 newly insured patients into one of its 10 community health centers, where newly hired social workers and mental health therapists provided services for some of the county’s poorest residents.