WASHINGTON - Nevada, Arizona and Colorado top the list of the country's fastest-growing states the past year, Census Bureau estimates show. States in the Midwest and along the East Coast lagged behind the rest of the nation.

North Dakota and West Virginia had the steepest declines, as slower economies continued to chase residents out of state while failing to attract enough newcomers to take their place.

The opposite occurred in Sun Belt states like Nevada, according to the bureau's first updated population estimates since the April 1, 2000, census. Lured by the warm climate and tourism industry, Nevada's population climbed 5.4 percent by July 1, 2001, to 2.1 million, according to the new estimates being released today.

"I hesitate to say when growth is going to stop. There's been a long westward movement in this country," said John Haaga, a demographer with the nonprofit Population Reference Bureau.

"More recently, it stopped being movement to the West Coast and filled in" other Western states, he said.

In Washington state, the population grew 1.6 percent to almost 6 million. The rate was slightly above the national average of 1.2 percent.

The national population grew from 281.4 million in April 2000 to 284.8 million in July 2001.

Weather and more vibrant economies have drawn more people to Southern and Western states than other regions for decades. Cities like Atlanta, Las Vegas and Denver act as a hub for growth spilling out into sprawling suburbs. A move to a bigger house or more land in the suburbs typically also means a longer commute for people working in big cities.

That suburban growth marked the rise in New Hampshire's population the past year, up nearly 2 percent to 1.3 million - the only state among the 10 fastest-growing located outside the South or West.

Much of that increase in New Hampshire came along the state's roughly 17-mile-long coastline between Massachusetts and Maine, an area that more Boston workers are willing to commute from, said Tyler Young, an assistant planner for the New Hampshire Office of Planning.

The important thing, though, is that those towns are not as densely packed as the New York City suburbs, said Barry Russo of Rye, N.H. He moved from Ridgewood, N.J., outside New York, three years ago and wants to help planners in his new town.

"It's definitely a more rural feel. It's a seacoast area, so development could overwhelm it," said Russo. "If I could prevent the 'Jerseyfication' of it, I'd like to be aware of it."

North Dakota saw the biggest population drop the past year - down 1.2 percent to 634,448. No state lost population between 1990 and 2000, but North Dakota did have the smallest increase - up by less than 1 percent.

West Virginia, Iowa and Louisiana were the only other states to decline the past year - all by less than 1 percent. Pennsylvania, New York, Nebraska and Ohio had slight increases.

Many of these states have faced the challenge of attracting new residents - and retaining younger residents - as farming communities continue to suffer financially, said Chuck Hassebrook, director of the Center for Rural Affairs.

"The real bent of these communities are the entrepreneurial background of these people," he said. "We aren't doing a lot right now to support that."

The bureau typically updates post-census estimates each year. Among other purposes, the data are used to help allocate federal funds to states.

Other highlights:

* California remained the most populous state, with 34.5 million. It was followed by Texas and New York.

* After North Dakota, New York had the steepest decline in net domestic migration. Unlike North Dakota, New York gained population because of higher international immigration.