Numbers from the U.S. Census released Thursday show the nuclear family slowly melting down in Southwest Colorado.

The numbers reveal striking changes in the way local family life has changed in the last decade.

The archetypal family – married parents with children living in a house they own – now accounts for a much lower share of the population, especially in rural areas.

Instead, more people rent.

More live in multigenerational families.

More live alone.

And there are fewer children around, especially in the rural areas of Southwest Colorado.

In fact, the median age increased by nearly five years in Montezuma County and by 7.6 years in Archuleta County, and the population older than 65 increased by more than 20 percent in La Plata and Montezuma counties.

Durango, on the other hand, seems to be getting more middle-aged. The city saw drops in both its child and senior citizen populations, and its drop in the nuclear family population was lower than most other towns and counties in the region.

The local numbers follow a larger trend toward smaller families and fewer homeowners, but the trends are amplified in Southwest Colorado.

“It’s not just a statewide trend but a national trend on the number of single-person households,” said Elizabeth Garner, the state demographer.

The trend has been building for decades, she said.

In rural areas, people older than 65 accounted for a larger share of the growth in people living alone than young people, according to an analysis of the Census numbers.

“We’re getting this from two ends,” Garner said. “The younger people are delaying marriage and deciding to live on their own. On the older end, we’ve got this really large baby boom population.”

Divorced or widowed baby boomers might account for the growth in the population of single seniors.

At the youngest end of the spectrum, children make up a small part of the population now. But families with two married parents raising their own children saw an especially steep decline.

Garner said she still needs to study the reasons behind the drop in the childhood population, but she suspects it’s a combination of lifestyle changes and an aging population.

On the other hand, the region saw a small uptick in the number of people living in a home with someone else’s children.

The economy has forced more households to combine, Garner said. Also, some families with two working parents find it convenient to have grandparents in the house.

Finally, Colorado’s increasing Hispanic population brings a tradition of multigenerational households, Garner said.

Rachel Cameron, program director at the Durango Family Center, said that of the center’s clients, 47 percent are married.

“We find that Hispanics still tend to live in nuclear families,” Cameron said. “Other Caucasians tend to be single or divorced.”

The family center, one of 23 members of the Family Resource Center Association, provides a variety of referral and direct-service help. It is funded largely by grants.

All these changing households are living in a changing mix of housing, too.

Every part of the region saw an increase in the housing stock, from 10 percent in Durango to more than 20 percent in the counties of La Plata, Archuleta and Montezuma. But more homes stood vacant, too. Vacancy rates in Durango and Mancos closely matched the state average of 10 percent, while Cortez and Bayfield had lower vacancy rates.

Seasonal homes account for a large part of the vacancy rate across the region. The Census counted vacant homes on April 1 – too early for summer sun-seekers or fall hunters, and too late for skiers.

Strikingly, Durango added second homes at an especially fast rate. In 2000, the Census counted just 100 unoccupied second homes inside the city limits. Ten years later, it counted 278.

La Plata County’s proportion of second homes dropped slightly, but it still remained far above the state average. One in nine homes in the county was counted as an unoccupied second home in 2010.

The Census Bureau generated Thursday’s numbers from last April’s Census questionnaires and follow-up questionnaires to find the reasons for home vacancies.

jhanel@durango herald.com Herald staff writer Dale Rodebaugh contributed to this report.