Manufacturing involves mechanically or chemically blending or transforming materials or substances into new products, or assembling component parts of manufactured products if the new product is neither a structure or some other kind of fixed improvement. Manufacturers normally sell their products through wholesalers or direct to industrial users. Some manufacturers in a few industries sell directly to household consumers, but where possible, these sales activities and outlet stores are classified as retail trade establishments.

The U.S. Census Bureau's censuses and current surveys of manufacturers' are the principal source of data about the Manufacturing sector of the U.S. economy. Data were first collected on manufacturing establishments during the 1810 decennial census. The decennial censuses continued to include collection of manufacturing data (with the exception of 1830) until 1900. From 1905 through 1919, the U.S. Census Bureau conducted a manufactures census every 5 years and then every 2 years thereafter, through 1939. As a result of World War II and war-related data collection, the U.S. Census Bureau resumed the 5-year schedule of censuses in 1947. Presently, economic censuses are taken for years ending in "2" and "7."

Manufacturing data also are collected for the Outlying Areas. The collection of manufacturing data for Puerto Rico began in 1901 (although not reported in every subsequent census). Guam and the U.S. Virgin Islands were added to the enumeration in 1958, followed by the introduction of data collection in the Northern Mariana Islands in 1982. Economic data from the Outlying Areas are collected in conjunction with the stateside enumeration (i.e., in years ending in "2" and "7").

In addition to the economic census, the Annual Survey of Manufactures (ASM) collects "census-type" data for noncensal years. Data are collected from a sample of manufactures and has been conducted since 1949.

Current Industrial Reports (CIRs), a series of annual, quarterly, and monthly surveys, some of which date from early this century, contain data on production, shipments, and/or inventories of specific products or on special subjects.

Title 13 the U.S. Code authorizes all of the economic census and surveys and requires response to the census and the majority of annual surveys. Also, this law assures that data provided by business establishments will remain confidential and be published in summary form only. To maintain strict enforcement of each establishments confidentiality, the Census Bureau makes certain no individual firms' operations can be identified in its printed or electronic publications. Furthermore, Census Bureau employees are subject to heavy penalties for violating the law's confidentiality provisions.

Manufacturing data from the 1997 Economic Census were collected and published according to the North American Industry Classification System (NAICS). This new classification system replaced the Standard Industrial Classification (SIC) coding system. The NAICS was implemented by the United States, Canada, and Mexico.