"In Florida, Pennsylvania and Delaware, retirement income isn't taxed," he said.
The county's overall population is still growing, though like much of Maryland's, more slowly than during the 1990s, according to Bronow's figures. Goldstein's report shows similar trends.
Howard's population has grown by 11 percent so far over the decade, almost double the state average. In absolute numbers, Howard grew fourth-fastest in Maryland behind Montgomery, Baltimore and Frederick counties, to a total of 274,995 by July 1, 2008.
Overall, census estimates show the county gained 27,153 people through July 1, 2007, though Bronow's estimate for the period is 34,832, based on completion of new homes and apartments over that period.
The federal estimate is lower, Bronow said, because it assumes foreign immigration to the county has remained the same in proportion to national trends over the previous five years, which may not be true. But Bronow said his use of housing completions could be flawed, too, if household sizes declined during the period. He noted that the census underestimated county population growth during the 1990s.
One stark aspect of population growth emerges when longer comparisons are made.
In 1969, two years after Columbia's first houses were built, only 60,092 people lived in Howard County, just over one-fifth of the current population. On average, the county grew by 4 percent a year, though that rate declined this decade to an average of 1.38 percent. Over the past five years, the average dropped even more, to 1 percent.
Peak one-year growth occurred in 1990, when population rose by 9,719 people. The smallest population growth occurred in 2005, when just 2,218 new residents arrived. The year from 2004 to 2005 also represents the smallest percentage growth at only 0.84 percent. The rate fell below 2 percent for the first time in the year from 2001 to 2002, when it was 1.6 percent.
