Experts say the phrase "bigger is better" fits the current trend in homes.

McMansions are sprouting across the country as an appetite for bigger homes just keeps on growing.

The Census Bureau said one in five American houses had at least four bedrooms in 2005. That's up from one in six in 1990, despite shrinking families and increasing costs for construction and energy.

Nationally, the average household size has shrunk slightly since 1990, to about 2.6 people. Meanwhile, the average new house grew by nearly 400 square feet, to 2,434 square feet.

And it's happening everywhere from the suburbs of Washington and Atlanta to southern Connecticut and out West in Utah.

In fact, Utah leads the nation with nearly 40 percent of homes having at least four bedrooms. As Utah mother Valerie Astle put it, "Our kids have more stuff. They need more living space."

Maryland ranked second at 28 percent. Colorado (26.2), Delaware (25.8), Minnesota (26.2), North Dakota (26.1) and Virginia (26.5) also have a large percentage of bigger homes.

The United Nations said American homes, on average, are nearly twice as large as those in many European countries, including Britain, France and Germany. Only Luxembourg comes close among European nations.

Among counties with populations of 65,000 or more, which was the threshold for the 2005 American Community Survey data, the following counties had the highest percentage of homes with four or more bedrooms: Davis County, Utah (49.4 percent); Fayette County, Ga. (45.5); Forsyth County, Ga. (48.5); Loudon County, Va. (44.6); Stafford County, Va. (43.8); and Utah County, Utah (45.7).

Cities with populations of 65,000 or more that stand out in the category include Allen, Texas (52.0); Centennial, Colo. (52.5); Naperville, Ill. (53.0); Sandy, Utah (63.8 percent); and Sugar Land, Texas (55.3).

Some other housing facts of interest include:

Single-family homes were the most common housing type (62.7 percent), and comprised more than eight out of 10 owner-occupied units (81.3 percent).
Apartments with 10 or more units were the second-most common housing type overall (12 percent).
The District of Columbia had 42.4 percent of housing units in this category. Hawaii and New York had 22.1 and 27.7 percent, respectively.
Among cities, about half of all housing units in Alexandria, Va., were in apartment buildings with 10 or more units; Miami Beach, Fla., had approximately 75 percent; and New York City had 54.2 percent.
The category comprising mobile homes or other type of housing (RV, houseboat, etc.) (6.5 percent) was the third most common.
Nearly one in five homes in New Mexico and South Carolina were mobile homes (17.4 percent and 18 percent, respectively).
Regionally, three-fourths of the nation's mobile homes were found in the South (56.1 percent) and West (20.2 percent). The remaining quarter were in the Midwest (16.2 percent) and Northeast (7.5 percent).
Townhomes were the fourth most common housing type (5.8 percent). The highest percentages of townhomes could be found in Washington, D.C. (26.4 percent); Maryland (20.1); Pennsylvania (18.1); Delaware (13.4) and Virginia (10.3). Approximately half of all housing units in the mid-Atlantic cities of Baltimore (49.7 percent); Camden, N.J. (54.8); Philadelphia (61.3); Reading, Pa. (58.5); and Wilmington, Del. (52.2) were this type.

As part of the Census Bureau's reengineered 2010 Census, the data collected by the ACS helps federal officials determine where to distribute more than $200 billion to state and local governments each year.

The 2005 ACS estimates are based on an annual, nationwide household sample of about 250,000 addresses per month, or 2.5 percent of the population a year. Geographic areas for which data are available are based on total populations of 65,000 or more. The ACS estimates released are for the household population and do not include populations residing in group quarters.