Maptitude for Redistricting/Maptitude for Precinct and Elections Management contain geographic layers which reflect updates to the census block geography made by Caliper Corporation. This geography is based upon the Census 2014 TIGER/Line files and includes additional updates to the geography to reflect block splits made by some states while creating state legislative plans for the 2010 redistricting cycle. Updates have also been made to census block numbering.
The Census 2014 TIGER/Line files include updates to higher level geography to make those geographies more accurate based on the annual Boundary and Annexation Surveys. Census blocks will not be redefined again until 2020, but they are split by the changes as well as by other corrections to higher level geography. For each of these split blocks, Census identifies each piece with a block suffix letter (uppercase).
Census maintains updated geography codes down to the Block Group level. Where boundary adjustments or corrections were made, this may be different at the tract, county or state level to the 2010 code. In such cases, simply appending the last three digits of the 2010 block code may create a duplicate. Caliper avoids such duplicates by appending a ‘c’ or ‘t’ to the current block group code followed by the 2010 block 4-digit code plus any Census suffix. This numbering prevents any block split that lands in a new tract or county from duplicating an existing block code and allows for an easy identification of such split blocks.
Where the 2010 and current full block group codes match, the block group 1-digit code is dropped since it is the leading digit of the4-digit block code.
Caliper had to further split some of the block in two states, Kentucky and Ohio to reflect the splits they created for legislative redistricting. These splits required manual renumbering by Caliper by adding a lowercase suffix letter.
The final coding used for census block geography is found in the Block field. These codes may be up to 18 characters for most states, expressed as the following:
SS represents the current state ANSI
CCC represents the current county ANSI code
TTTTTT represents the current tract code
BBBB represents the 2010 block code
X represents an optional Census block suffix
G represents the current block group code
c represents a renumbering by Caliper to avoid duplicate block codes (‘c’ if the county code was changed and ‘t’ if the tract code was changed)
For KY and OH, either of these format may have a lower case suffix if the state split a block during legislative redistricting, resulting in up to a 19 character block code.
The original 2010 block code is maintained by Caliper in the Block2010 field.
Congressional and State Legislative boundaries have been updated to reflect those in effect after the 2010 redistricting cycle. The codes for these assignments can be found in the Congress, UpperSLD and LowerSLD fields of the Census Block layer. For NH, the state house floaterials can be found in the CountyLD field.