Howard County led Maryland's 23 counties and Baltimore in census returns, with an 80 percent return rate - up from 76 percent in 1990.
Howard County's performance topped the statewide average of 69 percent and beat the next highest county - Montgomery - by 3 percentage points.
"The national response rate was 67 percent," said Andrea King, regional spokeswoman for the U.S. Census Bureau. "That's exceptional, especially since we were predicting a 5 percent drop nationally."
Baltimore had the region's lowest response rate, 53 percent, a 10 percent drop from 1990 and one of the worst responses of any big city in the nation. Anne Arundel County returned 74 percent, as did Baltimore County. Harford County returned 75 percent, and Carroll County returned 76 percent.