states and all 39,000 units of local government in the 
United States during the summer of 1989 as part of the 
Local Review Program -- all counties, all towns and 
townships, all cities and villages, all American Indian 
reservations. They provide several advantages over the 
Prototype files. (See Figure 3) 
• For the counties containing the Nation’s urban cores, 
the Precensus TIGER/Line files include the streets, 
street names, address ranges, and associated ZIP Codes 
that were identified as “missing” or “incorrect” during 
the Census Bureau’s initial address matching use of the 
TIGER data base to support the 1990 census. This 
process computer-matched a list of 53 million housing 
unit addresses located in the 345 largest urban areas of 
the United States. Staff in the Census Bureau’s regional 
offices clerically researched the 14 million addresses 
that did not match at that time, finding out why they did 
not match. They used the results of this research to 
improve the content of the TIGER data base in these 
rapidly changing urban areas. 
• The Precensus files contain updated geographic 
entity codes reflecting the January 1, 1988 boundaries 
reported to the Census Bureau by the nearly 39,000 units 
of local government covered by the 1988 Boundary and 
Annexation Survey. The 1988 codes appear in addition to 
the 1980 census code set available in the Prototype 
TIGER/Line files. 
• The Precensus files added a permanent record 
identification number — unique nationwide -- that will 
permit easier comparisons between the Precensus files 
and future versions of the TIGER/Line files. 
• The Precensus files were “edge-matched” in an 
attempt to make them capable of producing a “seamless 
map” of the entire United States or any group of adjacent 
counties. This process did not work perfectly; although 
all intersections of features with the edge of each county 
partition match, the “shape” points defining the edge of 
the partition between the intersections often do not. 
File Size (Megabytes) - Median6.2 
Figure 2 - Distribution of Precensus TIGER/Line Files by File Size 
Version 
Dates 
Available 
Vintage of 
Governmental 
Entity Boundaries 
Feature/Feature Name/Address Range 
Updates 
Voting 
District 
Codes 
Prototype 
Feb-Apr 1989 
1980 
All Counties 
(Initial TIGER Data Base 
Building Operations) 
No 
Precensus 
Oct 1989- 
Feb 1990 
1980 and 1988 
528 Counties 
(Major Urban Areas - 
Vendor Address List Matching/Resolution) 
No 
Initial Voting 
District Codes 
Aug-Oct 1990 
1980 and 1990 
(Initial) 
2,512 Counties 
(Prelist/Precanvass/Initial Local Official) 
Yes 
(Initial) 
1990 Census 
Jan-Mar 1991 
1980 and 1990 
(Final) 
All Counties 
(List Enumerate/Final Local Official) 
Yes 
(Final) 
Figure 3 - Planned Versions of the TIGER/Line Files 
497