FORT WORTH — Population: 661,850.With 37,000 people choosing to make Fort Worth their new home last year, the city led the region’s continuing population boom, spurred by single-family housing construction in the Alliance Corridor, according to a regional population estimate issued Thursday by the North Central Texas Council of Governments. Regionwide, 50,000 new homes were built as low interest rates continued to encourage home builders, according to the study, which measured population growth between Jan. 1, 2005, and Jan. 1, 2006. But nowhere does growth match Cowtown’s. “Fort Worth is a large city with developable land, and its boundaries aren’t set,” said Paul Winkelblech, research associate with the council’s research and information services. The 37,000 new residents — think of it as adding a city the size of Hurst — is nearly double the growth of 20,000 per year seen in Fort Worth since the 2000 U.S. Census, Winkelblech said. “And it could still expand northwest into annexed land, west and even southeast as well,” he said. Officials estimate that 70 percent of the city’s population growth was in the Alliance Corridor, bounded by Loop 820 to the south, Texas 114 to the north, U.S. 377 to the east and Lake Worth and Eagle Mountain Lake to the west. “The other area that’s growing is the south side, basically between I-35 and Lake Benbrook,” said Bob Riley, city development director. The population increase isn’t a surprise for the development department, where the number of building permits being issued has been accelerating for years. In fiscal 2000, Fort Worth issued 3,531 building permits. In fiscal 2005, it issued 8,752. In the first quarter of fiscal 2006 alone, Fort Worth issued about 3,700 permits — more than for all of fiscal 2000. “We have not experienced any slowdown,” Riley said. There are many reasons. Fort Worth has room to expand, unlike many suburbs between Fort Worth and Dallas. Favorable home mortgage rates have attracted apartment dwellers to the home market, and multifamily construction in 2005 dropped below 2004 levels by nearly 1,000 units. A diverse job market is also attracting new residents, Winkelblech said. “We’re no longer reliant on the airline industry and telecom — among industries, you can pretty much take your pick,” he said. Regional planners have noted the westward shift of the Metroplex population for years. Tarrant County led all counties in the 16-county North Central Texas region by adding 59,300 residents, for a total of 1,702,250. (Collin County continued to show significant growth, with seven of the top 10 fastest-growing cities located there.) Nearly half — 45 percent — of the region’s growth took place in five cities. In addition to Fort Worth, Frisco added 10,400 residents; Dallas, 10,300; McKinney, 10,050; and Grand Prairie, 8,300. Growth in those cities is considered to be average compared with previous years, officials said. The study was presented to the executive board of the council of governments Thursday afternoon. For Fort Worth leaders, the study’s information comes as no surprise and only emphasizes the need to shore up city services, particularly in new-growth areas where no services have been offered. “Because we continue to buck all the trends, we’re obviously experiencing some growth pains,” Mayor Mike Moncrief said. “We have our work cut out for us. It is our responsibility as a council and policymakers to ensure that the growth of this city is quality growth.” Specifically, Moncrief mentioned stormwater management and transportation as ongoing issues. While the Jan. 1, 2006, population study should be an accurate estimate of how many people are out there, demographic details about who is moving to Tarrant County won’t be available until 2005 census data are incorporated into a new research model, Winkelblech said. That model won’t be ready to be released until 2008, he said.