WASHINGTON (AP) -- Freight activity fell in March while a passenger index rose, according to government data released Wednesday.

The Transportation Department's Bureau of Transportation Statistics said its freight transportation services index, which measures changes in the output of services by the railroad, air freight and trucking industries, was 109.4 in March, 0.4 percent lower than the same month last year.

The freight index was down 1.9 percent from its February level, the largest monthly decline since August 2006. The index started in January 1990 at 66.6, and peaked in November 2005 at 113.1.

Canadian National Railway Co., Union Pacific Corp., Burlington Northern Santa Fe Corp. and CSX Corp. are among the largest railroad operators. Trucking companies include Con-Way Inc., Marten Transport Ltd., YRC Worldwide Inc. and Knight Transportation Inc. Air freight providers included FedEx Corp. and United Parcel Service Inc.

The passenger transportation index, which measures local transit, air travel and intercity railroads, gained 1.8 percent to 116.2 in March from a year earlier. That index, which also was up 1.8 percent from its February level, started at 70.5 in 1990 and peaked at nearly 118.2 last October.

The government's combined freight and passenger transportation services index in March was 110.7, a 0.2 percent gain compared with the same month last year, but down 1 percent from February. It started at 67.1 in 1990 and peaked at 112.6 in May 2006.

The March government data are preliminary and scheduled to be revised in four months.