The federal government spent $50 billion buying goods and services in the Washington area last year, an 18 percent increase over 2003, according to a George Mason University study released yesterday.

The overall increase in Washington area spending outpaced the growth of federal procurement spending nationwide, which rose by 10 percent. Spending by the Defense Department grew at 38 percent locally last year and, at $25.5 billion, accounted for most of the local total.

When federal payrolls are included, federal spending constitutes at least a third of the region's economy, according to the study, done by Stephen S. Fuller, director of the Center for Regional Analysis at George Mason University. It was underwritten by First Horizon Bank.

Stan Z. Soloway, president of the Professional Services Council, a contractor trade group, said the study's findings are not surprising given the government's ramped up need for help in the years since Sept. 11, 2001, and the Iraq invasion in 2003.

"This is a major center for government contracting. And we're in an environment where we've seen increases in the requirements for defense and homeland security," Soloway said.

Broken down by jurisdiction, the District was the site of $12.86 billion worth of spending, suburban Maryland accounted for $10.73 billion and northern Virginia lassoed $26.4 billion.

Fairfax County, including the areas of Fairfax City and Falls Church, accounted for 61 percent of northern Virginia's total, or $16.1 billion.

"It's the right labor force; it's the right kinds of services the feds are procuring," said Gerald L. Gordon, president and chief executive of the Fairfax County Economic Development Authority. "All the communities in Northern Virginia have historically been more aggressive than any of the other counties in this region."

Northern Virginia also dominated the region in defense procurement, with 71 percent of awards in 2004.

Putting aside Defense Department spending, federal contracting in the Washington region rose only marginally, 3.2 percent, from 2003 to 2004. The District's total of non-DOD spending actually dropped slightly last year.