...young family!'' By the middle of the '80s, Gwinnett was the nation's fastest-growing county. Now it's Forsyth County, along Gwinnett's northwestern boundary. The suburbs around Las Vegas and Denver have also been booming in recent...

...say. Dr. Ana V. Diez Roux of Columbia University looked at census blocks of 1,000 people in Jackson, Miss., Forsyth County, N.C., Washington County, Md., and suburban Minneapolis. Whites in the poorest neighborhoods were 70 percent...