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 CDP boundaries were inserted into the TIGER data base after census blocks were delineated, some CDP boundaries were not held as collection block boundaries and had to be suffixed. In Alaska, CDP boundaries were inserted and held as census collection blocks because of the difficulty in enumerating this State.

The boundaries of American Indian reservation and subreservation areas were held as census collection block boundaries where feasible for enumeration (a road into the area was a requirement for boundaries to be held), as were the boundaries of Alaska Native village statistical areas. This was done because of the difficulty in enumerating such areas.

The boundaries of urbanized areas (UAs) always follow the boundaries of tabulation census blocks. This is the only type of geographic entity boundary that UAs must follow, although most places are either entirely within, or entirely outside of, the UA boundary.

The Census Bureau requested that the State officials delineating Congressional districts for the 103rd Congress follow the boundaries of census tabulation blocks; most of them complied with this request. In the few instances where a Congressional district boundary subdivided a census block, the Census Bureau depicted the district boundary in its correct location and assigned the entire population of the census block to one district or the other in accordance with the State’s instructions.

The Census Bureau offers the opportunity for other Federal agencies, State agencies, and other data users to delineate nonstandard or special geographic tabulation entities on a fee basis. Such entities include school districts, traffic analysis zones, and other kinds of neighborhood- or community-based entities. The Census Bureau produces data for such special areas by aggregating the component census tabulation blocks. 11-18Census Blocks and Block Groups