For the first time, the wide-open spaces of the American West contain more people than the densely packed Northeast, and the rapid Western growth will continue, the Census Bureau says.

The bureau predicts that between now and the year 2000 more than half of all national population growth will occur in just three states California, Florida and Texas.The study adds that Texas is on the verge of crowding past New York as the nation's second most populous state. The projections call for Texas to surpass New York by 1995.

The Empire State now leads Texas 17.7 million to 17.2 million. But by 1995, Texas is expected to have just over 19 million people, with New York at only 17.9 million.

That transition is symbolic of the slippage in the Northeast, which has become the nation's least populated region, falling behind the West for the first time.

Bureau demographer Signe Wetrogen explained that the projections are based on assumptions about trends in births, deaths, immigration and movement within the country.

The Northeast has been declining in its share of the U.S. population, with less growth than other areas, she said.

"It is the one region with the highest share of population in the older ages, and has low birth rates," she explained.

Population shifts to the South and West in recent years have drawn away many people in the prime ages of 18 to 24, she said.

"So the (Northeast) region is left with more older people, and it's left without anybody to have more kids," she said.

But because it is smaller in area than other parts of the country, the Northeastern states remain the most densely packed. New Jersey leads the nation with more than 1,000 people per square mile.

Tables included with the report show that between 1987 and 1988 theWest region increased from 49.6 million people to 50.5 million. At the same the Northeast edged up only from 50.1 million to 50.3 million.

The 1988 estimates list the South with 85.1 million people, followed by the Midwest with 59.6 million.

By 1990 the projections call for the South to have 87.3 million people, followed by the Midwest, 59.8 million; West, 52.3 million and Northeast, 50.6. million. By the year 2000 the counts are expected to be South, 96.9 million; Midwest, 59.6 million; West, 59.4 million, Northeast, 51.8 million.

By 2010, the report adds, the West could surpass the Midwest and be the second most populous region.

The projections show California remaining the most heavily populated state, growing from 28 million people today to 29.1 million in 1990 and 33.5 million in 2000.

The U.S. is expected to grow from 243.3 million people in 1987 to 267.7 million in 2000, an increase of 24.4 million.

In that period, California is expected to add 6 million, Florida 3.5 million and Texas 3.3 million. The three-state total of 12.8 million people represents 52 percent of the projected national increase.