6 Largest Government Contractors

If it weren't for government spending, Lockheed Martin would likely be out of business. The company designs and manufactures satellites, spacecraft, missile defense systems and other products largely outside of the price range of private buyers. The company's biggest contract in 2012 was for the design and manufacture of a fixed-wing aircraft. The contract is valued at $3.48 billion.

Total Contracts: $9,143,329,000

Northrop Grumman is primarily a defense contractor engaged in manned and unmanned aircraft, missile systems, biodefense, military command centers, and aircraft refueling. This Virginia-based company is also the largest builder of naval vessels.

Total Contracts: $7,455,878,000

Boeing's largest source of revenue comes from the manufacture and sale of commercial aircraft, but roughly 31% of its 2011 revenue came from government contracts primarily from the U.S. government. The company is active in aerospace with $1 billion in contracts coming from NASA.

Total Contracts: $5,938,089,000

Science Applications International Corporation (SAIC) is a science and technology company engaged in a wide range of products and services. Some of these include cancer research, robotics, tsunami warning systems, new technology for crime labs and protecting troops in warzones.

Total Contracts: $5,665,503,000

Raytheon's primary business is defense-oriented with products ranging from air defense, marine combat systems and missile systems. Its best-known product is the Tomahawk cruise missile that is used by the U.S. Navy.

Total Contracts: $5,461,177,000

General Dynamics engages in the manufacture of submarines, destroyers and other defense products. A majority of its contracts come from the U.S. Navy. Its largest contract, a $2 billion contract, is for a new submarine.