Sources of data and definitions of variables in database for the U.S. Agricultural Sector for 1950-2007.

Accumulating a database of this size (nearly 1200 variables at present) and maintaining a reasonable level of accuracy in the various data series is a daunting task - especially for one who does not work in a major data collection agency. Data revisions are made frequently as analysts obtain new information. Different publications report different numbers because publication frequently occurs before data revisions can be incorporated. And, of course, occasionally transcription errors occur. My motivation for accumulating and maintaining this database is that over the past several years I have had need for a variety of statistical information related to the U.S. agricultural sector -- and particularly for studying the past history of this sector. In fact, this database was the source of much of the information in my book entitled Economic Trends in U.S. Agriculture and Food Systems Since World War II ( Iowa State University Press, 2001). Since a very general database such as this was not available elsewhere, I constructed it for my own use and have continued to maintain it over the years. My hope is that other individuals will find it useful -- even if it is not perfect. If so, my efforts will have been justly rewarded.

I must warn the user, however, that she or he will find that the data is not complete for all of the variables. Further, she or he may find some anomalies in the data recorded. I have relied exclusively on publications that were readily available to me for my sources of data rather than on detailed discussions with experts in the relevant areas. In some cases, data has not found its way into published documents but is only available directly from analysts in the relevant data collection agencies. Also, some agencies report different numbers than shown here for certain variables. Data revisions are always being made for the most recent five or so years so some discrepancies can be expected. Some revisions may go back further than five years, and occasionally an entire series may be redefined so that much or all of the data for a particular variable must be revised. In some cases, data may not have been collected for a particular variable for the entire time period, so data for the variable will not begin in 1950 and/or may end before the most recent year. All this is part of the world of economic analysis! If, however, users note any other errors or anomalies, a letter to that effect addressed to me at the Department of Agricultural Economics, Penn State University would be greatly appreciated.

As can be appreciated, a wide variety of sources have been used to obtain the data shown here. It would be impracticable to list sources for each of the nearly 1200 variables in this database, but the following sources are generally consulted first: Agricultural Statistics; Statistical Abstract of the United States; Economic Report of the President; Survey of Current Business; Federal Reserve Bulletin; Monthly Labor Review; and Economic Research Service's Agricultural Outlook -- Statistical Indicators. For many variables related specifically to the agricultural sector I consult specific sector situation and outlook reports published by Economic Research Service (e.g., Cotton & Wool; Feed; Fruit & Tree Nuts; Livestock, Dairy & Poultry; Oil Crops; Rice; Sugar & Sweeteners; Tobacco Vegetables & Melons; and Wheat), and various special reports published by National Agricultural Statistics Service (e.g., Agricultural Prices; Crop Production; Livestock Slaughter; Milk Production, Disposition and Income; and Vegetables). All of the above sources can be accessed via the web.) A somewhat different but very valuable source, particularly for general economy measures, is - Economic Time Series Pages. The latter is available on the web.

Statistics from earlier years are available or can be estimated from a variety of sources and will be detailed in a subsequent report. Two that the reader may wish to consider at the present time are: U. S. Department of Commerce. Historical Statistics of the United States, Colonial Times to 1970. Bureau of the Census. Washington, D. C. 1975, and U. S. Department of Commerce. Long Term Economic Growth: 1860-1970. Bureau of Economic Analysis. Washington, D. C. 1973.

Some Special Definitions
Specific Data Sources