WASHINGTON — The D.C. region’s busiest airport keeps getting more so.

BWI Marshall Airport had another record month in March with 2.1 million passengers. That’s 8.9 percent more than March 2015, and it was the ninth straight month for record-breaking passenger traffic.

Dulles International Airport dominates international flights in the Washington region, but international passenger traffic at BWI Marshall climbed 22 percent in March.

Air Canada, Alaska Airlines, British Airways, Delta Air Lines, JetBlue Airways, Southwest Airlines and Spirit Airlines all experienced passenger growth at BWI Marshall in March.

BWI Marshall had 23.8 million passengers in 2015, an all-time high, and edged out Reagan National Airport’s 23 million passengers last year.