This section presents statistics on farms and farm operators; land use; farm income, expenditures, and debt; farm output, productivity, and marketings; foreign trade in agricultural products; specific crops; and livestock, poultry, and their products.

The principal sources are the reports issued by the National Agricultural Statistics Service (NASS) and the EconomicResearch Service (ERS) of the U.S. Department of Agriculture. The information from the 1997 Census of Agriculture is availablein printed form in the Volume 1, Geographic Area Series; in electronic format on CD-ROM; and on the Internet site <http://www.nass.usda.gov/census/>.The Department of Agriculture publishes annually Agricultural Statistics, a general reference book on agricultural production, supplies, consumption, facilities, costs, and returns. The ERS publishes data on farm assets, debt, and income on the Internet site <http://www.ers.usda.gov/briefing/farmincome/>. Sources of current data on agricultural exports and imports include Outlook for U.S. Agricultural Trade, published by the ERS; the ERS Internet site <http://www.ers.usda.gov/briefing/AgTrade> and the reports of the U.S. Census Bureau, particularly U.S.Imports of Merchandise on CD-ROM, andU.S. Exports of Merchandise on CD-ROM.

The 45 field offices of the NASS collect data on crops, livestock and products, agricultural prices, farm employment, and other related subjects mainly through sample surveys. Information is obtained on some 75 crops and 50 livestock items as well as scores of items pertaining to agricultural production and marketing. State estimates and supporting information are sent to the Agricultural Statistics Board of NASS, which reviews the estimates and issues reports containing state and national data. Among these reports are annual summaries such as Crop Production, Crop Values, Agricultural Prices, and Livestock Production, Disposition and Income. For more information about concepts and methods underlying USDA’s statistical series, see Major Statistical Series of the U.S. Department of Agriculture (Agricultural Handbook No. 671), a 12-volume set of publications.

Farms and farmland-The definitions of a farm have varied through time. Since 1850, when minimum criteria defining a farm for census purposes first were established, the farm definition has changed nine times. The current definition, first used for the 1974 census, is 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.

Acreage designated as ‘‘land in farms’’ consists primarily of agricultural land used for crops, pasture, or grazing. It also includes woodland and wasteland not actually under cultivation or used for pasture or grazing, provided it was part of the farm operator’s total operation. Land in farms includes acres set aside under annual commodity acreage programs as well as acres in the Conservation Reserve and Wetlands Reserve Programs for places meeting the farm definition. Land in farms is an operating unit concept and includes land owned and operated as well as land rented from others. All grazing land, except land used under government permits on a per-head basis, was included as ‘‘land in farms’’ provided it was part of a farm or ranch.

Since 1945, an evaluation of census coverage has been conducted for each census of agriculture to provide estimates of the completeness of census farm counts. According to coverage evaluation results, the past five censuses of agriculture included an average of 92 percent of U.S. farms and 98 percent of agriculture production. The 1997 coverage evaluation program was designed to measure four components of error in the census farm counts. These components include undercount due to farms not on the mail list; overcount due to farms duplicated or enumerated more than once; undercount due to farms incorrectly classified as nonfarms; and overcount due to nonfarms incorrectly classified as farms. The first component, mail list undercount, is by far the largest component of coverage error. The percentage of farms missed in the census varies considerably by state. In general, farms not on the mail list tended to be small in acreage, production, and sales of agricultural products. For more explanation about mail list compilation and census coverage, see Appendixes A and C, 1997 Census of Agriculture, Volume1, reports.

Farm income-The final agricultural sector output comprises cash receipts from farm marketings of crops and livestock, federal government payments made directly to farmers for farm-related activities, rental value of farm homes, value of farm products consumed in farm homes, and other farm-related income such as machine hire and custom work. Farm marketings represent quantities of agricultural products sold by farmers multiplied by prices received per unit of production at the local market. Information on prices received for farm products is generally obtained by the NASS Agricultural Statistics Board from surveys of firms (such as grain elevators, packers, and processors) purchasing agricultural commodities directly from producers. In some cases, the price information is obtained directly from the producers.

Crops-Estimates of crop acreage and production by the NASS are based on current sample survey data obtained from individual producers and objective yield counts, reports of carlot shipments, market records, personal field observations by field statisticians, and reports from other sources. Prices received by farmers are marketing year averages. These averages are based on U.S. monthly prices weighted by monthly marketings during specific periods. U.S. monthly prices are state average prices weighted by marketings during the month. Marketing year average prices do not include allowances for outstanding loans, government purchases, deficiency payments or disaster payments.All state prices are based on individual state marketing years, while U.S. marketing year averages are based on standard marketing years for each crop. For a listing of the crop marketing years and the participating states in the monthly program, see Crop Values. Value of production is computed by multiplying state prices by each state’s production. The U.S. value of production is the sum of state values for all states. Value of production figures shown in Tables 834-837, 841, and 842 should not be confused with cash receipts from farm marketings which relate to sales during a calendar year, irrespective of the year of production.

Livestock-Annual inventory numbers of livestock and estimates of livestock, dairy, and poultry production prepared by the Department of Agriculture are based on information from farmers and ranchers obtained by probability survey sampling methods.

Statistical reliability-For a discussion of statistical collection and estimation, sampling procedures, and measures of statistical reliability pertaining to Department of Agriculture data, see Appendix III.