The following metadata was taken from the US Census website at http://www.census.gov/geo/www/cob/bg_metadata.html.
The data was downloaded from http://www.census.gov/geo/www/cob/bg2000.html#shapefile. The NYS statewide shapefile was projected from decimal degrees to UTM meters, Zone 18, Nad 83 and clipped to the 10 mile buffer of the Adirondack Park boundary.
For further information on these data sets follow the links for technical information below.
It is strongly recommended that the user of these data understand the definitions of block groups and census tracts. See other definitions at http://www.census.gov/geo/www/tiger/glossry2.html.
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Census Block Group
Geographic Area Description
A block group (BG) is a cluster of census blocks having the same first digit of their four-digit identifying numbers within a census tract. For example, block group 3 (BG 3) within a census tract includes all blocks numbered from 3000 to 3999. BGs generally contain between 600 and 3,000 people, with an optimum size of 1,500 people. Most BGs were delineated by local participants as part of the U.S. Census Bureau's Participant Statistical Areas Program. The U.S. Census Bureau delineated BGs only where a local, state, or tribal government declined to participate or where the U.S. Census Bureau could not identify a potential local or tribal participant.
BGs never cross the boundaries of states, counties, or statistically equivalent entities, except for a BG delineated by American Indian tribal authorities, and then only when tabulated within the American Indian hierarchy. BGs never cross the boundaries of census tracts, but may cross the boundary of any other geographic entity required as a census block boundary (see "CENSUS BLOCK").
In decennial census data tabulations, a BG may be split to present data for every unique combination of American Indian area, Alaska Native area, Hawaiian home land, congressional district, county subdivision, place, voting district, or other tabulation entity shown in the data products. For example, if BG 3 is partly in a city and partly outside the city, there are separate tabulated records for each portion of BG 3. BGs are used in tabulating data nationwide, as was done for the 1990 census, for all block-numbered areas in the 1980 census, and for selected areas in the 1970 census. For purposes of data presentation, BGs are a substitute for the enumeration districts (EDs) used for reporting data in many parts of the United States for the 1970 and 1980 censuses and in all areas before 1970.