Census Tracts (1990)

This polygon shapefile shows census tracts in the SPC region from the 1990 census. Census tracts are defined as " small, relatively permanent statistical subdivisions of a county. " The minimum population of a census tract is 1,200 people, and the maximum is 8,000 people. Note: Lawrence County was not part of the Southwestern Pennsylvania Commission's region in 1990.本多边形形状文件（shapefile）展示了1990年人口普查中宾夕法尼亚州西南部委员会（Southwestern Pennsylvania Commission，简称SPC）管辖区域内的人口普查区域（census tract）。人口普查区域被定义为‘县级行政区划内规模较小、相对固定的统计分区’，单个普查区域的人口下限为1200人，上限为8000人。注：1990年，劳伦斯县并未纳入SPC的管辖范围。