Apartment rents in the Washington area average about $690 a month -- about 60 percent higher than the national average of $432 -- making this region one of the nation's costliest for tenants, according to a new survey conducted by the National Apartment Association.

Rents were higher in only two other areas, San Francisco and Los Angeles, where tenants pay a monthly average of $794 and $791, respectively, for a typical apartment, according to the survey, which reviewed rental-apartment income and expenses in 43 metropolitan areas.

"It's been a relatively tight market in Washington until the last year or so, which means that {owners} can raise their rents faster," said economist Robert Sheehan of the National Apartment Association (NAA). "There are very few markets, other than California, where rents are higher."

In Washington, about half of the households are renters, compared with about 35 percent of adult households in the rest of the nation.

Renters elsewhere were better off than Washingtonians in almost all the regions surveyed, including Atlanta, where they pay an average of $472 a month; Orlando, Fla., where they pay $436; Chicago, at $608; Dallas, $402; and Seattle, $469.

Some of the nation's best deals from a tenant's perspective can be found in extremely overbuilt markets such as Oklahoma City, where rents average $272 a month, and in Colorado Springs, where the monthly average is $285.

The NAA study did not, however, include statistics on several costly rental markets, such as Boston and New York City. Sheehan said the group did not receive enough responses to its written survey from those two cities to ensure the information was statistically sound.

Boston and Manhattan, Sheehan said, are "certainly comparable" to Washington in terms of rents, but he added that rents there may be lower now than they were previously because the real estate slowdown hit those markets earlier and harder. In those two regions, Sheehan said, landlords have been forced to drop rents by 5 percent to 10 percent in the past year to attract tenants.

From a landlord's perspective, however, the apartment market in the Washington area is stronger than in most of the country. One advantage building owners have here is that many tenants are apparently loathe to move, according to the survey.

In the Washington area, only 43 percent of renters move out of their apartments each year, compared with a national average of 69 percent. Only Cleveland has a lower turnover rate, with 39 percent of its tenants moving each year. In some cities with heavy student or seasonal populations, such as Denver and Phoenix, almost all the tenants leave each year.

"Even students don't give up their units here," Sheehan said. "They keep it 12 months a year even if they're not here in the summer because there's a relatively tight market closer in {to the city}."

Sheehan said turnover rates rise in markets where there is an oversupply of apartments and where tenants learn they can cut costs by moving.

In Washington, he said, few landlords are cutting rents. Instead, he said, they still are generally offering leasing incentives, such as one month free rent to new tenants.

In addition, he said, in the Washington area and other regions where home prices are high, large populations of long-term renters are developing. While young families once would have moved quickly from rental apartments to homes of their own, "we now have a permanent class of baby boomers who will never become owners," Sheehan said.

The NAA survey, conducted last spring, included about 584,000 units nationwide, with a heavy emphasis on the South, Southwest and West, where many large property management companies are headquartered. Only apartments in projects of at least 100 units were included. Few rent-controlled buildings were included in the survey. The average unit size was 848 square feet, about the size of a small two-bedroom apartment, and most of the properties were located in garden-style complexes.

The survey also found:

Apartment building management is a lucrative business in the Washington area. Salary and personnel costs here amounted to about $765 per unit per year, compared with a national average of about $565 per unit. Management fees across the country averaged about 4.5 percent of gross potential rent.

"Economic vacancy," or total rent not collected as a percentage of the annual gross potential rent, ranges from 9 percent in the Northeast to 13 percent in the Southwest, a slight overall improvement from last year.

The nation's lowest economic vacancy rate -- 6 percent -- was posted in Baltimore, with the Washington area close behind at 8.2 percent. The survey tracked economic vacancy rates rather than traditional vacancy rates as measured by empty units because, according to the survey's authors, it better reflects a property's health over the course of a year.

Real estate and personal property taxes varied widely, from a low of $146 per unit in Oklahoma City to a high of $955 in Chicago. The national average was $464, while Washington averaged $640.

Repair and maintenance costs rise as properties age, with the highest expenses in the northern Midwest while the lowest were in the South and Mountain states.