In 1991 Paul Verrochi created a business plan to consolidate the fragmented ambulance industry, following a similar "rollup" strategy used by Waste Management. The company was formed with the merger of Regional Ambulance (Alameda and Contra Costa counties, CA), Vanguard Ambulance (Santa Clara County, CA), and Buck Ambulance (Portland, OR). Laidlaw acquired American Medical Response in 1997, after previously acquiring MedTrans, a San Diego-based high quality EMS provider operating in California, Washington, Nevada, and Texas. Laidlaw continued acquiring 138 more companies, growing to over $1B in revenue before acquiring AMR. In 2004, Laidlaw sold EmCare and American Medical Response to Onex. Onex formed Emergency Medical Services Corporation as the parent of its two acquisitions. EMSC went public in December of that year. In 2011, EMSC was acquired by Clayton, Dubilier & Rice. On June 12, 2013, EMSC changed names to Envision Healthcare Corporation. On September 8, 2017, Envision Healthcare Corp. announced that American Medical Response would be sold to KKR & Co. LP in an all-cash deal worth US$2. 4 billion. In March 2018, American Medical Response became a subsidiary of Global Medical Response.