Raleigh, North Carolina, offers the best quality of life in America, according to a recent Portfolio.com/bizjournals study.

But there’s a point worth noting. Those rankings were confined to major markets that have more than 750,000 residents. What if you prefer to live somewhere smaller?

A companion study now provides the answer, proclaiming Boulder, Colorado, to be the quality-of-life leader among metropolitan areas with populations between 250,000 and 750,000.

Portfolio.com and bizjournals compared 109 medium-size markets in 20 statistical categories. The partners used the same formula as in their earlier study, giving the highest scores to areas with healthy economies, moderate costs of living, light traffic, impressive housing stocks, and high-powered educational systems.

Boulder, which is 25 miles northwest of Denver, has a metropolitan population of 300,000. It’s a hub for high-tech industries and the home of the University of Colorado, two characteristics that have attracted a young, highly educated workforce.

Boulder earned high scores across the board in the quality-of-life study, placing among the 10 best markets in 13 of the 20 categories.

These are among its strengths:

• Fifty-six percent of Boulder’s adults have bachelor’s degrees, easily the strongest concentration in any midsize metro. Just eight other markets are above 35 percent.
• Slightly more than half of Boulder’s workers hold management or professional jobs, the sector that pays the highest salaries. The only other market above 50 percent is Ann Arbor, Michigan.
• There is a generous inventory of large homes in Boulder. Eighteen percent of its houses have at least nine rooms, a figure that only a pair of Utah metros, Provo and Ogden, can top.
• Boulder is seventh out of 109 markets in two key financial categories. Its median household income of $65,960 is the seventh-highest in the study group, and its poverty rate of 5.8 percent is the seventh-lowest.

Portfolio.com and bizjournals based their quality-of-life rankings on data from the U.S. Census Bureau’s 2006-2008 American Community Survey, which was released late last year. (See the details on the methodology.)

The rest of the top 10 among medium-size markets included four other cites in the western mountain states of Colorado (Fort Collins and Colorado Springs) and Utah (Provo and Ogden). Michigan had two cities in the list (Holland and Ann Arbor). And Wisconsin, Iowa, and New Hampshire each was represented with one market a piece (Madison, Des Moines, and Manchester, respectively).

(For a slideshow that goes into depth about the top 10, click here. And click here to download a PDF of the entire list of 109 markets.)

The Sunbelt dominates the opposite end of the quality-of-life scale, with medium-size markets from Alabama, California, Georgia, Louisiana, and Texas holding the nine lowest positions.

Last place belongs to Visalia, California, a metro with 422,000 residents. It’s located roughly midway between Los Angeles and San Francisco.

Visalia has the lowest percentage of management and professional workers in the study, 23.9 percent, which is less than half of Boulder’s 50.1 percent. Visalia is also dead last in the share of adults with college degrees, 12.7 percent.