< PrevNext > 35. Northrop Grumman Falls Church, Va. Share 2017 U.S.-Booked Air Volume: $103 millionConsolidated U.S. TMC: BCDBTN estimates that defense contractor and aerospace conglomerate Northrop Grumman in 2017 spent about 6 percent less on U.S.-booked air travel than in 2016. Northrop Grumman's business travel—including air and rail travel, hotel stays and rental car use—generated about 143,330 metric tons of carbon dioxide equivalent emissions in 2017, up 13 percent year over year. The company employed approximately 70,000 people at the end of 2017, about 3,000 more than 12 months prior. Sales revenue increased 5 percent in 2017 to $25.8 billion. Its backlog, a measure of firm orders not yet fulfilled, declined 5 percent to $42.9 billion. The company in June 2018 closed the $9.2 billion acquisition of rocket, missile and satellite manufacturer Orbital ATK, subsequently renaming it Northrop Grumman Innovation Systems.