Nearly one-third of residents in Champlin and Brooklyn Park are under 18. Married couples live in eight of 10 households in Andover. And the Twin Cities suburbs with the largest percentage of workers who commute 45 minutes or more are Ramsey, Blaine and Andover.

The northern suburbs are communities of extremes, according to a Metropolitan Council analysis of three years of U.S. Census Bureau data from 2005 to 2007. Brooklyn Center was the most racially diverse suburb (with 49.1 percent persons of color) and Shoreview among the least (0.0 percent). Champlin ranks highest in the metro for having 31 percent of its population under the age of 18; in Blaine it was a Twin Cities low, at 25.1 percent.

One in five residents in New Hope was 65 or older -- one of only three metro area suburbs with that distinction. (Roseville and Edina were the others.) But Andover's 65-and-older population was a metro area low, at 3.8 percent, closely followed by Ramsey, at 4.7 percent, and Champlin, Maple Grove, Blaine, Brooklyn Park, Coon Rapids, all under 10 percent.

"We have the whole gamut when it comes to socioeconomics," Anoka County Administrator Terry Johnson said of communities north of Minneapolis and St. Paul. "Why is that? It's happened over time."

Two waves of development help define the northern suburbs, Johnson said. Developing the Twin Cities' major airports in the southern metro region affected visionaries' plans for the northern suburbs. In the 1970s there was still plenty of available land, and that attracted droves to Anoka County, Johnson said.

Then, a second wave of development followed in the late 1980s. Word spread that Anoka County was more than a large, sprawling sod farm along the Mississippi River. As growth in many communities in the Twin Cities began to stagnate, people were still moving to Anoka County. And the age of the population in many of those northern suburbs is reflected by the comparatively late development of those cities.

Marrieds and not-so

Married couples dominated households in still-growing Andover (a metro-leading 78.4 percent) and Ramsey (second in the Twin Cities, at 74.5 percent).

Fewer than one-third of the households in Minneapolis had married couples, but Fridley, at 44.2 percent, and Brooklyn Center, at 44.8 percent, were among the handful of suburbs in which married couples lived in fewer than half the households.

Not surprisingly then, Ramsey boasted the metro's lowest percentage of households in which people lived alone, only one in 10 (or 10.5 percent), with Andover a close second (10.9 percent). Andover had the highest percentage of households with married couples with children under 18 -- with 44 percent.

Brooklyn Park was also among the suburbs least likely to have married couples with children under 18 living in the same household (27.3 percent). Yet, the percentage of kids 18 or younger living in Brooklyn Park was among the highest in the Twin Cities -- 29.9 percent.

One in four Brooklyn Center residents spoke a language other than English at home. Andover, Ramsey, Shoreview, Coon Rapids and Champlin were among cities in which fewer than 10 percent of residents' primary language was English.

Brooklyn Center, New Hope and Fridley produced the lowest median household incomes among Twin Cities suburbs -- all under $51,000 -- while Maple Grove ($89,866) and Andover ($88,170) were among the highest.

Mobility and stability

Most mobile of the developed northern Twin Cities suburbs were New Hope and Brooklyn Center, where more than half the households moved into their current residences in 2000 or later. Among suburbs considered by the Met Council to be "currently developing," Andover, Ramsey and Maple Grove showed surprising stability, with fewer than half of their residents having moved in after 2000.

If you lived in Andover during the survey, you owned your own home -- or at least 97 percent of the residents did. Residents in Ramsey, Blaine and Maple Grove were also among the most likely to own homes in the Twin Cities. But New Hope, Fridley and Brooklyn Center were among the developed suburbs with the lowest homeowner rates.

Homeowners in Shoreview, Crystal and Champlin were least likely to have experienced severe housing-cost burdens, paying 50 percent or more of their incomes to housing costs. Among the suburbs with the greatest housing-cost burdens were Brooklyn Park, Brooklyn Center and New Hope. In each case, at least 15 percent of home- owners struggled with severe housing costs.

Paul Levy • 612-673-4419