Release Date: February 2009
Source: Census of Agriculture, National Agricultural Statistics Service, U.S. Department of Agriculture (for 1969-2007 data); ``Average size of farms by County, years 1890 to 1997,'' originated by Chris Kahle, Iowa Department of Natural Resources, Iowa Geological Survey, compiled February 2003 (for 1890-1964 county data); ``Historical Statistics of the United States: Colonial Time to 1970,'' U.S. Bureau of the Census (for 1890-1964 state data).
Notes:

A farm is defined as any place from which $1,000 or more of agricultural products were produced and sold, or normally would have been sold, during the census year. Beginning in 1997, operations receiving $1,000 or more in Federal government payments were counted as farms, even if they had no sales reported in the census year.

The 2002 Census introduced a procedural change in the method for counting farms. As a result, data for 2002 and beyond are not directly comparable with data collected in earlier census years. The values shown in ``1997adj'' reflect a backward revision of the 1997 values using the 2002 methodology, and are provided to allow comparison with newer values.

Due to significant changes in methodologies and definitions used in conducting the Census of Agriculture over time, all longitudinal changes should be interpreted with caution.