Florida and Texas had 10 of the 11 metropolitan areas that grew most rapidly from 1980 to 1984, the Census Bureau said yesterday in a report chronicling the remarkable and continuing population increase in southern and western states.

The two states not only had most of the areas that grew more than 20 percent from 1980 to 1984 but also eight of the next 10 fastest-growing areas -- those that grew 15 to 19 percent -- and 32 of the next 55 areas that grew 10 to 15 percent.

"Essentially this is a continuation of a shift in population to the South and West that has been going on since 1970," said Don Starsinic of the Census Bureau. "Ninety percent of the population growth has been occurring in the South and the West. Migration is still continuing, though not quite as strong as in the 1970s."

If the shifts continue, they would further boost southern and western strength in the House of Representatives after the next census in 1990 at the expense of the once-dominant Northeast and Midwest.

The bureau also found that three of the eight large Frost Belt metropolitan areas that were losing population during the 1970s -- New York, Philadelphia and St. Louis -- are now growing. Buffalo, Cleveland, Milwaukee, Detroit and Pittsburgh are still losing.

In New York, the gain was 267,600 (or 1.5 percent) for the huge metropolitan region, which the Census Bureau defines as New York City, Long Island, Westchester County, other nearby New York counties and parts of Connecticut and New Jersey. Its total population is 17.8 million.

Starsinic said that even the city of New York gained -- about 93,000 between 1980 and 1984 -- after having lost population during the 1970s.

He said the reason seems to have been a stabilization of jobs and an end to the economic shrinkage that occurred during the 1970s.

"The same thing is true for much of the Northeast," he said.

The bureau found that of 277 metropolitan areas -- which consist of central cities and their surrounding suburbs and related areas -- 37 had 1 million or more residents. Charlotte-Gastonia-Rock Hill, N.C., and Salt Lake City-Ogden, Utah, were newcomers to the 1 million population list.

Among metro areas with 1 million population or more, Houston-Galveston-Brazoria, Tex., grew most rapidly, 15 percent, with Dallas-Fort Worth second at 14 percent. The Houston area's growth enabled it to climb past Washington, D.C., into eighth place in size, even though the Washington metropolitan area grew 5.5 percent to 3,429,400.

Most of the 11 fastest-growing areas were small to medium ones; Midland, Tex., at 38 percent, led the list, with Anchorage, Alaska -- the only non-southern area -- second at 30 percent. Others among the top 11 were Naples, Ocala, Fort Pierce, Fort Myers, Melbourne-Titusville and West Palm Beach, Fla., and Bryan-College Station, Odessa and Austin, Tex.