<
 
 
 
 
>
hide You are viewing an archived web page, collected at the request of United States Department of Agriculture using Archive-It. This page was captured on 09:26:50 Mar 10, 2012, and is part of the USDA Economic Research Service collection. The information on this web page may be out of date. See All versions of this archived page. Loading media information

June 2005  issue of AmberWaves

Amber Waves Heading

United States Department of Agriculture | Economic Research Service Search   GO!  
Current Issue
All Issues
spacer Amber Waves Home

 

Up Front
  Feature Articles

Findings

Gleanings
  Data Feature

Indicators

Profiles

 

About Amber Waves

  E-mail notices

 

ERS logo
USDA's Economic Research Service

 

AmberWaves June 2005 > Indicators > Behind the Data

Print this page Print | E-mail this link E-mail | Bookmark & Share Bookmark/share | Translate this page Translate | Text only Text only | resize text smallresize text mediumresize text large
title "Indicators"

indicators tabbehind the data tabresearch areas tabon the map tab

spacer
Population Interaction Zones for Agriculture
Population interaction zones, 2000

Widespread conversion of rural lands to urban uses is an issue challenging all levels of government. To provide policymakers with information useful for projecting future changes in land use, ERS has created a system to classify remaining farmland into “population interaction zones for agriculture” (PIZA). These zones represent areas of agricultural land use in which urban-related activities affect the economic and social environment of agriculture. In these zones, population interactions with farm production activities increase farmland value, change farm enterprises, and elevate the probability of conversion to urban-related uses.

Though closely related to the existing ERS county-level Urban Influence Codes and census tract-level Rural-Urban Commuting Area Codes, PIZA is a complementary system that provides codes for much smaller 5-kilometer squares. In addition, the PIZA codes provide a continuous and cardinal (rather than ordinal) measure of population interaction, which is especially useful for some analyses.

Designation of the zones begins with use of common Geographic Information System (GIS) software to assign an index number to each 5-kilometer cell in a grid laid out across the contiguous 48 States. The “population interaction index” (PII) measures the influence that nearby population exerts on agricultural land in each grid cell. Each PII is a continuous measure that accounts for both population size in all grid cells within a 50-mile radius and their distance from the target grid cell. The index increases as population increases, and/or as distance between agricultural land and that population decreases.

In order to assign cells to either a “rural” zone or a “population interaction” zone, thresholds for PII were established for each of 20 Land Resource Regions (LRRs) defined by USDA's Natural Resources Conservation Service. Thresholds were established near the upper end of the range of index numbers for grid cells in the most rural census tracts of each LRR. Within each LRR, index numbers below that threshold represent rural levels of population interaction, which exist even in the absence of urban-related population interaction. Any grid cell whose index exceeds the threshold is classified into a “population interaction zone.” Cells initially classified into the population interaction zone are further classified into one of three categories, yielding a four-level classification: rural (little or no urban-related population interaction) and low, medium, and high population interaction.

The indices (PII) and zone codes (PIZA), which can be used to classify any geographic point in the 48 contiguous States, are available on the ERS website. GIS software is necessary, however, to retrieve the indexes and zone codes and relate them to any given geographic point.

Contact: Vince Breneman

 

PDF icon Get all Indicators in Adobe PDF Format (1 Mb)

red leaf rounded colored spacer
red leaf

This article is drawn from...

rounded color spacer

Measuring Interactions Between Urban-Related Population and Agricultural Production Activities

ERS Population Interaction Zones for Agriculture (PIZA)

All outlook reports
Get recent releases, links to the latest data, an outlook release calendar, outlook-related special reports, and a brief overview of the outlook for U.S. agriculture.

AO tables
Get the statistical indicators formerly provided in Agricultural Outlook magazine.