HAMPTON -- One of the biggest stories to come out of the latest Census data, according to demographer Peter Francese, is the drop in the population of people under the age of 18 in New Hampshire.

Hampton was one of the towns in the Seacoast that saw the biggest drop of its under-18 population from 2000 to 2010.

Hampton dropped 15.6 percent compared to North Hampton which dropped 9.6 percent and Portsmouth which lost 3 percent of its young residents.

Rockingham County saw an 8 percent decrease in people under the age of 18, while the state dropped 7.2 percent.

Hampton officials said this week the reasons for the decline are likely many. Among them are the fact people are having less children, the decline of winter rental housing at the beach and the overall affordability of moving to Hampton.

While Hampton's under-18 population declined, under-18 populations in Hampton Falls and Seabrook saw incremental increases.

"The thing that immediately comes to mind is perhaps that our property values during the period increased in relative terms at a faster rate then a lot of communities," selectmen Chairman Richard Nichols said this week. "That has implications for people in an age range to have children and their ability to afford that."

Nichols said 10 years ago, the average assessed value of a single-family home in Hampton was $173,000. Now it is $364,000.

While taxes on an average single-family home 10 years ago were $3,944, today the cost is about $5,869.

"My gut feeling is that I don't think it was a huge increase that would drive people out," Nichols said. "It's more of function of people of child-bearing age moving in at a much lower rate to replace those people."

Hampton School Board Chairman Rosemary Lamers said she was not surprised to see such a decline.

All three schools in Hampton have experienced a decline of enrollment during the last 10 years.

While 10 years ago enrollment hovered between 1,475 and 1,500 students, it is now down to 1,260.

"It isn't a surprise," Lamers said of the Census results. She noted the school conducted a study back in 2005 which predicted similar declines.

Lamers credits a number of factors to the population decline, including the fact the district has seen a sharp decline over the years in enrollment of transient students.

In the past, Hampton would always receive a bump in student population during the school year due to families moving into winter rental housing at Hampton Beach.

"The population at the beach has declined for two reasons from what I understand," Lamers said. "First, is the cost of housing and second, is the availability. Years ago, there used to be a lot more cottages but a lot of homeowners have converted them to 12-month homes."

Bob Preston, of Preston Real Estate of Hampton and Seabrook, said over the years, there has been a significant decrease in winter rentals at the beach.

"In the old days, there wasn't a lot of rental places in and around the area so people were forced to come to the beach," Preston said. "That isn't the case anymore. We also haven't had any big construction jobs where a (construction worker's) family would move here because of employment."

But Preston believes the decline of children under the age of 18 has more to do with the fact people are having less children.

"In the old day, people had three or four kids," Preston said. "I come from (a family of) five. Today, there is a lot of families with just two."

Lamers said she also believes the lack of jobs in the area as well as the cost to live in Hampton could also be factors.

"People in general are more transient in the work force because you go where the job is," Lamers said. "Also watching the number of foreclosures in town is indicative the prices having gone to a point where people can't really afford them."

Looking at adults, the population of those ages 18 and older grew by 18.5 percent in Stratham, 15.1 percent in Greenland, 8.4 percent in Hampton and 0.6 percent in Portsmouth.