Howard County's population is growing faster than projected and is expected to increase by more than 50 percent in the next 25 years -- likely aggravating community tensions already rising about schools, roads and development.
State planners estimate that by April 1 the county had 218,400 residents, compared with 187,328 in 1990 when the county's current growth policy was enacted.
The county's estimate for April 1 was about the same as the state's estimate. But the most recent population estimate by county demographers -- as of June 1 -- is a bit higher, 219,286 people.
This number is higher than had been projected, and the difference is a matter that goes beyond mere numbers.
County officials have been making detailed plans concerning schools, roads and public services based on their earlier projections, and Howard slow-growth advocates have been challenging officials for years -- saying official population projections were too low.
The county's General Plan, a growth-policy blueprint approved five years ago, predicted this year's population would only be 210,500. And as recently as last year, both state and county planners predicted the county population would be just 215,150.
"It wouldn't be so bad if they were overestimating, but when they underestimate, they're setting us up for problems down the road," said Valerie McGuire, a southern Ellicott City day-care provider and activist who has urged county officials to keep a tighter rein on growth.
Since the economic boom of the late 1980s, Ms. McGuire and a host of other residents have complained that the county's roads, schools and other public facilities have not been keeping pace with its rapid growth.
The county's population now is expected to grow 55 percent by 2020 to 338,000 people. In the county's 1990 General Plan, Howard's population was expected to peak at 285,500.
The problem of lagging population projections is not confined to Howard County, said Roselle George, a demographer for the county Department of Planning and Zoning: Demographers across the nation have been underestimating the size of households.
Average household size -- declining steadily for most of this century -- leveled off five years ago, much to the surprise of demographers, she said.
It wasn't until last year, after the state and county collaborated on a set of population forecasts, that the trend began changing the assumptions that the county used to calculate populations.
Ms. George said she compared the number of children in school with the number of homes in the county and could see that Howard County families, at least, were not getting any smaller.
At the same time, state and federal demographers were noticing the same trend elsewhere, caused by a variety of reasons: Larger families from other countries have been immigrating here; children have been living with their parents longer; and more children are returning to live with their parents.
One trend observed in Howard County is that residents are living longer, and more elderly residents are sharing their homes and moving into basement or attic apartments, said Joseph W. Rutter Jr., county director of planning & zoning. Also, recent birth rates have not declined as much as expected, he said.
From April 1990 to April 1995, there were 11,993 more births than deaths in the county, according to the state Office of Planning. But newcomers to the county were the biggest source of growth: During the same five-year period, Howard County welcomed 19,050 new residents.
Faster-than-expected population growth should help county school officials make their point with county government about the need for more funds to build more new schools, said Sandra H. French, vice chairwoman of the county school board.
"I am not surprised at all by the numbers being higher," she said. "I am not a statistician, but I do look at human behavior."
Families moving into Howard County, she said, are more affluent and more conservative, she said. "They're starting to have more children," she said, "because they can afford the children, and because they have strong family values."
County government officials have been at odds with the school board about how to accommodate growing school enrollment, which was about 36,000 last year and is expected to grow by 1,800 pupils this September. The board wants to build more schools, while County Executive Charles I. Ecker wants to build additions for existing schools.
County officials also have been warning that with declining family sizes, Howard could find itself closing schools within the not-too-distant future.
But, in light of the new population projections and the leveling off of the decline of family size, Ms. French challenged that logic: "How can they say that people aren't going to have as many children than they are now?"
But Mr. Ecker doesn't consider the unanticipated population growth a cause for alarm.
"Right now, it doesn't have any effect," he said. "If we keep watching it, and it goes on for another couple of years, then it could have an effect."