ATLANTA -- Delta Air Lines, the world's biggest carrier, said Wednesday it will impose a $15 fee to check a first bag, becoming the last of the six legacy airlines to impose such a fee.

It also said Wednesday it is cutting certain other fees as it aligns its policies with those of Northwest Airlines, which it acquired last week.

Atlanta-based Delta says that effective immediately, for traffic on or after Dec. 5, customers flying within the U.S. will be charged $15 for the first checked bag and $25 for the second checked bag when traveling domestically, consistent with Northwest's existing policies.

Delta also said it is eliminating SkyMiles and WorldPerks award ticket surcharges, reducing reservation sales direct ticketing charges and eliminating curbside check-in administrative fees.