Bans on single-use plastic bags — one of the most pervasive sources of pollution — are taking effect in cities and states across the U.S. as efforts to combat global plastic production pick up. Plastic bags were widely introduced to American consumers in 1979 and were marketed as preferable to paper because they are durable, waterproof and have many functions, according to the United Nations Environment Programme. Until the early ’80s, paper bags were standard for carrying groceries.