Commuting Pima County employees put on more miles and used more energy driving to work during the first decade of the 2000s, a new study shows.

The reason is probably continued suburban growth. Employees moving farther onto the edge of the metro area is probably what sharply boosted their commute distances, energy use and contribution to greenhouse-gas emissions, county officials said.

But in the past two years, a significant increase occurred in the number and percentage of county employees who bicycled and rode buses to work, a separate county government survey showed.

Here are the numbers:

• From 2000 to 2010, energy use and greenhouse-gas emissions attributed to Pima County employee commutes to work rose about 45 percent, says the Pima Association of Governments study.

• The number of miles driven by commuting county employees rose 46 percent, from about 28.7 million miles in 2000 to 41.9 million miles in 2010, the study showed.

Yet from 2000 to 2010, the county workforce actually declined 4.6 percent, from 6,832 in 2000 to 6,511 in 2010.

These figures suggest county employees are driving farther from home to work and carpooling or using public transportation less, said Linda Mayro, director of the county's office of sustainability.

During much of that decade before the real estate market crashed in 2007, Vail, Sahuarita, Marana, the edges of Tucson, and even Red Rock were booming with new subdivisions, Mayro noted.

"There's no public transportation in these far-flung areas, and the cost of housing is less expensive there," Mayro said.

Overall, "we can't dictate where people buy houses, or where they live," County Administrator Chuck Huckelberry said.

In the separate survey of 3,100 county employees, however, the average weekly miles driven by county employees dropped and the percentage of employees who rode the bus to work rose by about 11 percent each.

The percentage of county employees who used some form of alternative transportation to work rose from 19.2 percent in 2010 to 27 percent in 2012, the survey said.

By the numbers


Rise in county employees' commuting miles from 2000-2010


Percentage using alternative transportation in 2012


Pima County is Southern Arizona's ninth-largest employer, with 6,076 full-time workers this year, the Star 200 survey shows.

Contact reporter Tony Davis at or 806-7746.