BLM is an acronym for the Bureau of Land Management. The BLM is responsible for managing and conserving over 245 million surface acres of land, mostly in the western United States. The BLM also manages 700 million acres of sub-surface mineral estate throughout the nation.
For more information on the BLM you can visit their web site by clicking on the BLM link.
Source: Bureau of Land Management. "About the Bureau of Land Management". 2011. Accessed on 9 September 2013. Available at: http://www.blm.gov