World Wide Catalog 1995 Summer/World_Wide_Catalog_InfoMagic_Summer_1995.iso/pages/wwwcensr.gov/tiger/intro94.asc

Text File | 1995-06-11 | 13KB | 287 lines

                      TIGER/Line(R) Files, 1994



                            Introduction

TIGER/Line(R) Files, 1994, Developed by the Bureau of the
Census╩Washington:  The Bureau [producer and distributor],
1994.

Type of File and Geographic Extent

The TIGER/Line(R) Files, 1994 are extracts of selected
geographic and cartographic information from the Census
Bureau's TIGER (Topologically Integrated Geographic Encoding
and Referencing) System.  The 1994 TIGER/Line files (version
21) reflect an increase in the editing of address ranges and
new ZIP+4 Codes derived from the latest matching with the
Address Control File and the United States Postal Service
(USPS) files.  In addition, they reflect an improvement in
the consistency of highway names and feature identifiers
throughout the United States.

These files have a similar format and structure as the
TIGER/Line(R)  Files, 1992 but include field definition
changes and five new record types that accommodate
information that is new or information previously supplied
separately in another Census product.  Two record types (RT F
and RT G) have been deleted which addressed the additions,
corrections, and updates to the inventory of geographic
entities made since the 1990 census.

The TIGER/Line Files, 1994 are being released by county or
statistically equivalent entity based on the January 1, 1994,
boundaries.  There will be 3,182 files covering the 50
States, the District of Columbia, Puerto Rico, and the
outlying areas.

Principal Differences Between the 1992 TIGER/Line Files and
the 1994 TIGER/Line Files

Major Changes to Field Definitions

Major changes have been made to the field definitions in
Record Type 1.  The geographic area codes on this record type
now represent current geography, rather than the 1990 census
tabulation geography, except for census tract and block which
remain 1990 geography.  In some instances the current state
and county combined with the 1990 census tract and block will
create nonexistent geographic areas.  Use only the 1990 state
and county with the 1990 census tract and block.
The Census Alaska Native Regional Corporation (ANRC) codes
have been eliminated from Record Type 1.  They have been
replaced by two fields that will be used only by participants
in the 2000 Redistricting Data Program Block Boundary
Suggestion Project (these fields will be blank-filled in this
version of the TIGER/Line files) and the American Indian
Trust Land Flags (not carried in earlier versions of
TIGER/Line).  The American Indian Trust Land Flags may
contain two values, "I" for individual trust land or "T" for
tribal trust land.  The imputed address flags on Record Types
1 and 6 may contain three values, "0" for address range end
is not imputed, "1" for address range end is imputed, and "2"
for address range end should not be used for geocoding.

In Record Type 3, all references to 1980 geographic area
codes were eliminated.  The fields were replaced with
geographic area codes used to tabulate the 1990 census that
previously appeared in Record Type 1.  In addition, Record
Type 3 includes the current census geographic area codes for
the American Indian/TJSA/TDSA/ANVSA areas, and the Alaska
Native Regional Corporations.

Record Type 7 excludes all Key Geographic Locations (KGLs).
These now appear in Record Type 9.

Changes have been made to some of the field definitions for
Record Type A.  Space was added for the Census Transportation
Planning Package Area Code using some of the previously
reserved space at the end of the record.  The fields for the
101st and the 103rd Congressional District Codes have been
replaced with those for the 106th and the 108th; these will
be blank on this release.  Note:  The Congressional District
Codes for the 104th Congress, are provided on new Record Type
S as Current Congressional District.

New Record Types Added

The 1994 TIGER/Line files include five new record types --
Record Types 9, C, H, S, and Z.  Record Type 9 consists only
of Key Geographic Locations (KGLs) in the TIGER data base for
the current county or statistically equivalent entity.
Record Type 9s purpose is to provide the linkage between a
building (KGL) with its own ZIP+4 Add-On Code and the actual
street number/street name for the building.  The KGLs
contained in this record type are not included in Record Type
8 or Record Type 7, and there is no LAND (Landmark
identification number) for these KGLs.

Record Type C incorporates information that was supplied
separately in the TIGER/Geographic Name File (GRF-N).  Record
Type C provides a unique list of all geographic entities with
their code, name, and status.  The FIPS Year field may have
three values, "90" for name and codes valid for the 1990
census, "94" for geographic name and codes valid for the
current year, or blank when the geographic name and codes are
the same for 1990 and 1994.  Multiple records for the same
geographic entity show change or correction over time.

Record Type H will describe the history of the TIGER/Line IDs
when complete chains are split or merged.  Two fields (HIST
and SOURCE) provided for on Record Type H currently are not
yet maintained in the TIGER data base and will be blank in
this version.

Record Type S provides space for more geographic area codes
to identify polygons.  Several of the fields on this record
type are for use by participants in our programs to return
proposed geographic area codes to the Census Bureau.  Record
Type S is similar in construction to Record Type A and is
linked to Record Type P.  There is a Record Type S for every
polygon in Record Type P.  There is no assurance that the
Census Bureau will populate any of these new fields that
currently are not in the TIGER data base.  The Water field
may have two values, "0" for land or "1" for water.

A field in Record Type S is entitled Congressional District
Number, Current.  In some instances the current state
combined with the current congressional district will create
nonexistent geographic areas.  The current congressional
districts must be used with the 1990 state code and not the
current state code.  Listed below are the valid congressional
district codes and a brief description of what the code
means.


Valid Codes  Description

00           At large representative, Congressional District
              covers the entire state

01-52        Congressional district number
             (California having the largest number of
             districts at 52).

98           Nonvoting delegate

99           No representative


Record Type Z is a new record.  It links to an address range
in both Record Type 1 and Record Type 6.  If the RTSQ field
contains a "0", then the +4 Postal Add-On Codes apply to the
address ranges in Record Type 1 with the same TLID.  If the
RTSQ field contains a number greater than "0", then the +4
Postal Add-On Codes apply to the Record Type 6 with the same
TLID and RTSQ values.


Record Types Deleted

The 1992 TIGER/Line files included two new record types,
Record Types F and G, which have been deleted in the 1994
TIGER/Line files.  Record Type F showed geographic codes as
of January 1, 1990, that had been corrected to resolve
questions local officials raised about the 1990 census data
tabulations.  Record Type G showed geographic codes
(generally as of January 1, 1992) in those situations for
which geographic entities reported changes in their
boundaries during the Census Bureau's annual survey of
governmental units.

Boundary and Area Changes

Since the release of the 1990 Census TIGER/Line files, the
Census Bureau has shifted and reshaped some line features
including boundary lines.  These changes involve the
realignment of features associated with corporate boundary
corrections and changes.  The shape and area of the
geographic entities depicted in the 1994 TIGER/Line files may
differ from the earlier version despite the fact that they
represent the entity as it existed on January 1, 1990.
However, the inventory of 1990╩census tabulation entities
remains the same.

Address Ranges and ZIP Codes (R)

In almost all counties or county equivalents, the Census
Bureau has edited potential address ranges and ZIP Codes(R).
The 1992 TIGER/Line files previously included new address
ranges only for street segments that contained no address
range information in earlier versions of the TIGER/Line(R)
files.  In this version, the new address ranges and ZIP Codes
have been edited for overlaps or other inconsistencies.

Figure I-1 is a map showing the residential address range
coverage in the 1990 Census TIGER/Line files, by
county/statistical equivalent in the United States1 .  On
this map, address range coverage is based on the total number
of street segments with address ranges relative to the total
number of street segments in the county/statistical
equivalent.

Figure╩I-2 is a map showing the proportion of city style
addresses included in the address ranges in the Census TIGER
data base for each county/statistical equivalent relative to
the total number of residential addresses in the
county/statistical equivalent.  Addresses included in the
1990 census that are not covered by an address range in the
Census TIGER data base either were rural addresses, Post
Office (PO) box addresses, or city style addresses that the
Census Bureau could not match to a feature in the TIGER data
base.

Appendix A lists the address range coverage category for each
county and statistically equivalent entity.  Even though the
maps in Figures 1 and 2 measure address range coverage in
different ways, they do show counties for which full to
limited address range coverage is available in the
1992╩TIGER/Line files that did not have as much (or any)
address range coverage in earlier versions.

File Availability

The 1994 TIGER/Line files are available on CD-ROM and other
media from Customer Services Branch, Data User Services
Division, Washington, DC 20233-8300; [phone].  For
pricing information, contact Customer Services Branch, Data
User Services Division.

How to Use This Documentation

The structure of this document is based on data content
rather than record type content.  For instance, all
references to addresses appear in one section, with
references to other sections that contain relevant
information.  In order to make the document easier to use as
a reference, the text contains some repetition from section
to section.  This documentation was originally prepared for
the 1992 TIGER/Line files.  Only certain chapters have been
updated for the 1994 TIGER/Line files.

Chapter 1 describes the basic concepts about TIGER and the
TIGER/Line(R) product.  It discusses the topology in the
Census TIGER data base, the terminology used in this document
to describe the geographic data, and provides an overview of
the record types that make up the TIGER/Line(R) files.  The
documentation for the 1994 TIGER/Line files utilizes the
Federal Information Processing Standards (FIPS) Spatial Data
Transfer Standard (SDTS) nomenclature for geographic objects.
Anyone new to the TIGER/Line(R) files or unfamiliar with
these terms should review this chapter.  This chapter was
updated for 1994 TIGER/Line files.

Chapter 2 discusses the principle identification numbers that
form the basis for record linkage discussed throughout the
documentation.  This chapter was updated for 1994 TIGER/Line
files.

Chapter 3 discusses the attributes for the line, polygon, and
landmark geographic data types.

Chapter 4 defines the types of geographic entities and entity
codes that appear in the TIGER/Line(R) file.  Because the
geographic entity codes are associated with both lines and
polygons, the documentation discusses them in this separate
chapter.  This chapter also identifies some of the
fundamental relationships among the different types of
geographic entities.

Chapter 5 summarizes the data quality aspects of the
information in the TIGER data base using the SDTS quality
modules.

Chapter 6 lists the contents of the 1994 TIGER/Line files
record types and provides a detailed description of the data
fields in each.  The intent is that one will use Chapter 6 in
conjunction with Chapters 3 and 4 to locate the positions of
specific data fields in the 1994 TIGER/Line files.  This
chapter was updated for 1994 TIGER/Line files.

Census TIGER, TIGER/Line(R), TIGER/SDTS(TM), and TIGER/UA
Limit(TM) are trademarks of the U.S. Bureau of the Census.
ZIP Code is a registered trademark of the U.S. Postal
Service.1 The county boundary file for Figures I-1 and I-2
comes in part from Environmental Systems Research Institute,
Inc.