TIGER/Line Shapefile, 2016, Series Information for the Current Census Tract State-based Shapefile

The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the
U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB).
The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to
stand alone as an independent data set, or they can be combined to cover the entire nation.

                             Census tracts are small, relatively permanent statistical subdivisions of a county or equivalent entity, and were defined by local
                             participants as part of the 2010 Census Participant Statistical Areas Program.  The Census Bureau delineated the census tracts in
                             situations where no local participant existed or where all the potential participants declined to participate.  The primary purpose of
                             census tracts is to provide a stable set of geographic units for the presentation of census data and comparison back to previous
                             decennial censuses.  Census tracts generally have a population size between 1,200 and 8,000 people, with an optimum size of 4,000
                             people.  When first delineated, census tracts were designed to be homogeneous with respect to population characteristics, economic
                             status, and living conditions.  The spatial size of census tracts varies widely depending on the density of settlement.  Physical
                             changes in street patterns caused by highway construction, new development, and so forth, may require boundary revisions.  In addition,
                             census tracts occasionally are split due to population growth, or combined as a result of substantial population decline.  Census tract
                             boundaries generally follow visible and identifiable features.  They may follow legal boundaries such as minor civil division (MCD) or
                             incorporated place boundaries in some States and situations to allow for census tract-to-governmental unit relationships where the
                             governmental boundaries tend to remain unchanged between censuses.  State and county boundaries always are census tract boundaries in
                             the standard census geographic hierarchy.  In a few rare instances, a census tract may consist of noncontiguous areas.  These
                             noncontiguous areas may occur where the census tracts are coextensive with all or parts of legal entities that are themselves
                             noncontiguous.  For the 2010 Census, the census tract code range of 9400 through 9499 was enforced for census tracts that include a
                             majority American Indian population according to Census 2000 data and/or their area was primarily covered by federally recognized 
                             American Indian reservations and/or off-reservation trust lands; the code range 9800 through 9899 was enforced for those census tracts
                             that contained little or no population and represented a relatively large special land use area such as a National Park, military
                             installation, or a business/industrial park; and the code range 9900 through 9998 was enforced for those census tracts that contained
                             only water area, no land area.