Since 1910 the federal government has issued census information on metropolitan areas, described variously as metropolitan districts, metropolitan counties, industrial areas, or labor market areas. In 1949 the term Standard Metropolitan Areas was introduced and defined as dense urban populations with common economic and social characteristics to enable all federal statistical agencies to utilize the same boundaries when they published data for analyzing metropolitan problems. In order to achieve a more objective definition of a metropolitan area, the criteria were revised and reissued in March 1958. "Statistical" was added as an identifying phrase to describe more accurately the objectives of the definition. This concept aided in the collection of comparable statistics so that socioeconomic factors such as labor force, industrial output, and criminal records could be used in analyses. An SMSA was officially defined as one or more counties containing a core city of at least 50,000 inhabitants, or two cities with a combined population of at least 50,000, provided the smaller had at least 15,000 persons. The area must have a "metropolitan character," or at least 75 percent of its labor force in nonagricultural employment. There must be evidence of an economic and social integration between the central city and its county and outlying counties for the area to qualify as an SMSA. Measures of integration range from the percentage of labor force living outside but working within the central city to population density, newspaper circulation, data on charge accounts, traffic volume, and others. An urban region may have more than one SMSA when the criterion of integration is lacking, such as Fort Worth, Dallas, and Sherman-Denison, where each was defined as a separate and distinct SMSA although their areas' boundaries were contiguous. In 1970 Texas had more SMSAs than any other state, with a total of twenty-four. The designation standard was later dropped, and three area classifications based on population were adopted. These are metropolitan statistical area, the basic unit, a freestanding urbanized area with a population of at least 50,000; primary metropolitan statistical area, having two or more MSAs and 100,000 or more population; and consolidated metropolitan statistical area, having two or more PMSAs with a total population of 1,000,000. In 1990 the United States had 261 MSAs of which twenty-eight were in Texas; seven of seventy-one PMSAs in the United States were in Texas, and two of twenty United States CMSAs were in Texas. These were the Dallas-Fort Worth PMSAs (population about 4,000,000) and the Houston PMSA, Galveston-Texas City PMSA, and the Brazoria PMSA (population about 3,750,000). The Dallas-Fort Worth CMSA gained over 800,000 in population between 1980 and 1990 to become the eighth largest metroplex in the nation. Cities want to obtain the highest possible statistical designation because many congressional appropriations are made according to size. Businesses use population data for market analysis and advertising. Texas's rate of population growth is greater in the MSAs than in the state as a whole. Most of these MSAs are in the eastern part of the state. Texas MSAs include only 48 of the 254 counties but 80 percent of the population.