A pollconducted by CNN of more than 1,000 adult Americans found that 57 percent of them are opposed to the controversial practice of mountaintop removal mining.The cable news network conducted the survey in advance of the premiere of "Battle for Blair Mountain: Working in America," a documentary produced by Soledad O'Brien. The piece looks at Blair Mountain in West Virginia, a mountain that played a large role in the unionization of the coalfields in the early 1900s. Mining companies hold permits on the mountains, and could choose to surface mine, which activists could ruin the environment and bury historical artifacts forever.In the poll, which was conduced by ORC International from July 18 to 20, 57 percent of respondents opposed mountaintop removal, while 36 percent said they support the process. The poll's overall sampling error is plus or minus three percentage points.In their articleabout the poll, CNN quotes several who support mountaintop removal, who say others may not understand the practice, or that it's sanctioned by law.