America is an increasingly metropolitan nation, with more than three out of four people living in urban areas, the Census Bureau reports.

The nation's 282 metropolitan areas grew to 187.1 million residents as of July 1, 1987, up 1 percent from the year before and compared to just 0.3 percent growth in rural areas, the bureau reported Thursday.Florida and Texas included nine of the nation's fastest-growing metropolitan areas, and all 10 leaders were in the Sun Belt, the study found.

Only one change occurred among the 10 largest metro areas, with Washington, D.C., edging up one spot to edge out Houston for the No. 9 ranking.

The Washington area added 78,300 people between 1986 and 1987 while economically plagued Houston lost 21,000, the bureau said. The 1987 figures show Washingto with 3,646,000 people to Houston's 3,626,300.

Naples, Fla., was listed as the fastest-growing metro area, climbing 49 percent in this decade to 127,900, placing it at 215th among metro areas. That's up from 265th place in 1980.

Most of the fastest-growing areas had relatively smaller population bases, however. That means it doesn't take as many new arrivals to provide a large percentage increase.

The fastest-growing metropolitan area of 1 million or more was Phoenix, census officials noted. It grew by 30 percent in this decade, edging out Dallas-Fort Worth, which was up 27 percent.

While 76.9 percent of Americans live in the nation's 282 metropolitan areas, nearly half, 48.9 percent, reside in the 37 areas with more than a million residents each, the report showed.

Metropolitan areas are designated by the federal Office of Management and Budget and are used for many federal programs. In general, they consist of a central city with at least 50,000 residents and the surrounding region which is economically linked to that city. Many metropolitan areas include several major cities, often crossing state lines.

Washington, for example, includes portions of Virginia and Maryland; the New York metro areas extends into New Jersey and Connecticut and Chicago also counts sections of Indiana and Wisconsin.

New York remains firmly atop the list of metro areas, including an estimated 18,053,800 people, up from 18,019,800 in 1986 and 17,539,532 in the 1980 census.

Second is the Los Angeles region with 13,470,900, followed by Chicago, 8,146,900; San Francisco, 5,953,100 and Philadelphia, 5,890,600.

Rounding out the top 10 were Detroit, Boston, Dallas, Washington and Houston.

While the census study didn't include growth rates for all metro areas, here is the list of the fastest-growing metro areas between 1980 and 1987:

1. Naples, Fla., 127,900, up 49 percent.

2. Ocala, Fla., 181,300, up 48 percent.

3. Fort Myers, Fla., 294,600, up 44 percent.

4. Fort Pierce, Fla., 215,400, up 43 percent.

5. Austin, Texas, 738,000, up 38 percent.

6. Melbourne, Fla., 374,900, up 37 percent.

7. West Palm Beach, Fla., 790,100, up 37 percent.

8. Las Cruces, N.M., 128,800, up 34 percent.

9. McAllen, Texas, 378,600, up 34 percent.

10.Orlando, Fla., 934,700, up 34 percent.