Northwest Airlines Corp. and Delta Air Lines Inc., the fourth- and fifth-largest carriers, respectively, at T.F. Green Airport in Warwick, combined yesterday to create the world’s largest carrier after the U.S. Justice Department gave its approval.

Delta, the third-biggest U.S. airline by traffic, and number-six Northwest take the top global spot as the largest carrier from AMR Corp.’s American Airlines. Delta chief executive officer Richard Anderson leads the new company, which keeps Delta’s name and Atlanta headquarters.

Delta agreed to buy Eagan, Minn.-based Northwest in April in an all-stock deal, and their shareholders endorsed the plan last month. The new Delta will have $35 billion in annual sales and 75,000 employees, and deliver $2 billion in new revenue and cost savings, the airlines have said.