County Boundary Data for Each State

Extracting the boundaries of each county is useful for many applications of the TIGER dataset. The following Java-based tools allow one to download the TIGER Lines corresponding to any state of your choice. This boundary data is much smaller than the entire dataset for the state, and hence the tool avoids downloading the entire dataset. Merging the boundaries of adjacent counties is a slight problem, as TIGER Lines are not necessarily consistent across counties. We give a simple (imperfect) solution with the Merge program below.

For our user's convenience, we have also provided (1) a simple drawing tool to visualize the boundaries so extracted, and (2) downloadable pre-processed boundary data for each state.

BUG FIX: The following bug was recently fixed (12/1/2001). When the integer part of longitude turns from two to three decimal digits (in western USA), the minus sign in longitude disappears from our data below. For example, bounding coordinates for NY are (-79762418, -71778137, 40477408, 45010840). But for CA, it is (114132652, 124470153, 32528832, 42009518). The longitude in the bounding box for CA are missing their negative signs: Thanks to Alex Gleyzer for this bug report.

Java Source Codes

links.txt:
The url links used to download Tiger Dataset by TigerDownloader.
TigerDownloader.java:
A java program to download the boundary information of counties in a state.
Here is a sample output, the boundary information of counties in New York State.
Merge.java:
A java program to merge the segments output by TigerDownloader into monotone chains.
Here is a sample output, the boundary monotone chains of counties in New York State.
Draw.java:
A little java program to visualize the boundary information.

Downloadable Boundary Data Files