Minnesota-based 3M is building a $150-million research and development facility at its Maplewood campus. The 400,000-square-foot building will eventually house 700 scientists and researchers working on 3 of 3M’s five businesses – electrical and energy, safety and graphics and industrial. The company has invested heavily in research centers around the world, but company executives insist the United States remains the company’s innovation hub. 3M spent $1.6-billion in global research last year. It provides about 12% of Maplewood’s entire tax base. Locally, 3M is the 2nd largest taxpayer in Brown County, contributing nearly $250,000 annually, or around 2% of the total Brown County tax revenue.