TIGER

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TIGER?

• INLS 110-111
• GIS Digital Information
• Uses, Resources Software Tools

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Census Bureau

• Factfinding one of America's oldest activities
• Early 1600's, census taken in Virginia
• people were counted in nearly all of the British
  colonies that became the US
• First census taken in 1790
• counted 3.9 million inhabitants
• Sole purpose of the censuses surveys is gather
  general statistical information

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Census Bureau Long Form Replacement
Slide Show American Community Survey
American Community Survey Update (July 2002)
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TIGER? Overview

• Acronym Topologically Integrated Geographic
  Encoding and Referencing
• System developed at Census Bureau
• Supports mapping needs for Decennial Census
  other Bureau programs
• Geographic database features cover the nation

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TIGER? data base

• Vector model digital data (topological)
• census geography
• Federal Agency Dept of Commerce
• Bureau of The Census
• Widespread format contains important data

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Census Geography Models GBF/DIME TIGER?
GBF/DIME model
TIGER model
Image Source Demers, Michael. N. (2000). 2nd Ed.
Fundamentals of Geographic Information Systems.
p. 113. fig 4.16.
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Census Geography ModelTIGER? up close
Image Source Clarke, Keith C. (2001). 3rd Ed.
Getting Started with Geographic Information
Systems. p 92.
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Example TIGER? Image
Image Source Clarke, Keith C. (2001). 3rd Ed.
Getting Started with Geographic Information
Systems. p 91.
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TIGER? data base creation

• Automated map scanning
• Many scanned directly from USGS 1100,000-scale
  topographic quads
• Manual map digitizing
• Standard data keying
• Computer file matching

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TIGER? Files Hierarchal Structure

• Begins at National Level 2 sub-branches
• Regions
• Divisions
• States 2 sub-branches
• Counties 1 sub-branch
• Census Tracts/Block Numbering Areas
• Block Groups
• Blocks

Slide Show Census 2000 Geographic Concepts and
Products
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TIGER/Line? Files

• Public digital database of geographic features
• roads, railroads, rivers, lakes, political
  boundaries, census statistical boundaries, etc.
• longitude/latitude, name, type of feature,
  address ranges, relationship to other features,
  etc.
• Coverage entire U.S.
• NOT graphic images of maps requires GIS
• Does NOT include demographic statistics

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TIGER/Line? Files

• Census Bureau releases periodic extracts of data
  base to the public
• Extracts known as TIGER/Line? Files
• Most recent version is Urban Area (UA) Census
  2000 TIGER/Line.
• Files in ASCII text format only

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Census Units

• Census Tracts
• Boundaries follow major streets or natural
  features
• Population in each Tract approx. 4,000
  regardless of size
• Block Groups
• Boundaries counterminious with census track
  boundaries
• Population in each Group approx. 1,000
  regardless of size

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Census Units(cont)/Street Units

• Blocks
• Smallest geographic area formed by street
  segments
• Coded by 3 digit numbers 1st represents block
  group, last 2 are consecutive unique within
  block group
• Street Unit
• Street segment (between nodes)
• Address Range (odd, even, which end is highest )

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TIGER/Line? Naming Format

• One TIGER/Line file for each county or
  equivalent.
• File names consist of TGR the 2-digit state
  FIPS code the 3-digit county FIPS code
• i.e. TGR01031.ZIP for Coffee County, Alabama.
• Each state folder contains individual county
  files as well as a Counts file.
• COUNTSnn.TXT files ("nn" is the state FIPS code)
  show number of records for each record type by
  county for a state. If the count for a particular
  record type is 0, record type does not exist for
  that county.

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TIGER/Line? Metadata

• Datum
• NAD83 used for 48 contiguous states, D.C.,
  Alaska, Puerto Rico, Virgin Islands. (1995
  later)
• NAD27 coordinate datum used for the 1994
  earlier versions (except Hawaii Pacific Island
  Areas)
• Regional datum's used for Hawaii Pacific Islands

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TIGER/Line? Metadata (cont)

• Projection
• not in a mapping projection
• Outside UA
• original art in UTM projection USGS 1100,000
  DLGs
• after scanning coordinates transformed into
  projection-less latitude longitude
• Urban Areas
• based on USGS 7.5 minute topographic quadrangles,
  enlarged to 119,200 rescribed.
• derived from the GBF/DIME files