More people than ever have become stay-at-home workers.

The U.S. Census Bureau says the number of telecommuters, workers who most days go off to the office in their pajamas, is on the rise in the D.C. area and nationally.

The percentage of people in the United States working exclusively from home went up from 4.8 percent in 1997 -- more than 6 million people -- to 6.6 percent in 2010, or more than 9 million people, the Census Bureau said.

The top telecommuting cities, by percentage of workers at home most of the week:
1. Boulder, Colo., 10.9 percent
2. Medford, Ore., 8.4 percent
3. Santa Fe, N.M., 8.3 percent
4. Kingston, N.Y., 8.1 percent
5. Santa Rosa-Petaluma, Calif., 7.9 percent
Source: U.S. Census Bureau

The number of workers who spend at least one day at home also went up, from 7 percent to 9.5 percent of the workforce.

One reason for the up-tick is that technological improvements have made it much easier, and feasible, the report shows.

In the D.C. region, about 141,634 people, or about 4.9 percent of the workforce, worked from home most of the time in 2010, according to the Census Bureau. That's up from 109,072 in 2005.

Those numbers are lower than results from a 2010 survey by the Metropolitan Washington Council of Governments, which showed that about 600,000 people in the congested Washington region telecommute at least occasionally.

The council's Nicholas Ramfos said the differences may have been caused by differences in how the surveys were conducted or what areas were included in them. But, he said, one thing is clear: Telecommuting is growing, and that's good for the region.

"It helps reduce congestion and improves air quality," Ramfos said, adding that it also benefits companies by boosting productivity and giving workers flexibility. "Employee morale goes up a little more when you don't have to sit in traffic for three hours a day."

Herndon resident and Advisory Board employee Pete Simpkinson, of Herndon, started teleworking in 2011. The media relations manager for the Advisory Board, a health and higher education consulting firm, swapped telecommuting for what had been an 80-minute drive and Metro ride to his D.C. office.

"I'm in a role where it's just as efficient for me to telework as it is for me to be in an office on a daily basis. And it helps with my work-life balance," he said.

He says his company selects workers to telework on a case-by-case basis, but that it makes him more productive.

"In the morning," he said, "I can be responsive right out of the gate."