It hardly comes as news that the Census Bureau estimated this week that Baltimore City lost more than 3,000 people from July 1, 2007, to July 1, 2008. There have only been three years in the last 20 in which the city has gained population, part of a decades-long decline from Baltimore's million-plus peak long ago.

What's more surprising is that Baltimore County lost population in the same period. Not much -- just 212 people out of a population of more than 785,000. But it does reflect a change in the trends in the region's population. When the county first surpassed the city in population in 1994, the city was losing 10,000 or more people a year, and the county was gaining 5,000-7,000 a year. The numbers don't prove that the city's losses were the county's gain, but it's a pretty good bet. Now both of those trends appear to be cooling off. The county isn't gaining as many people as it once was, and the city, even including this year's dip, isn't losing nearly so many.

The city has been grappling with the issues of population decline for a very long time. But the end of steady population growth would be a big change for the county. A government that has been focused on managing development and holding the line on the property tax rate could, in the years ahead, find itself dealing with a very different set of problems. Unless the county abandons its long-standing (and wise) policies of limiting rural development, it will quickly reach the point at which it stops growing altogether. Is the county's leadership prepared for that day?