The data on industry were derived from answers to Questions 36 through 38. Written responses to the industry questions are coded using the industry classification system developed for Census 2000 and modified in 2002 and again in 2006. This system consists of 269 categories for employed people, including military, classified into 20 sectors. The modified 2006 census industry classification was developed from the 2006 North American Industry Classification System (NAICS) published by the Executive Office of the President, Office of Management and Budget. The NAICS was developed to increase comparability in industry definitions between the United States, Mexico, and Canada. It provides industry classifications that group establishments into industries based on the activities in which they are primarily engaged. The NAICS was created for establishment designations and provides detail about the smallest operating establishment, while the American Community Survey data are collected from households and differ in detail and nature from those obtained from establishment surveys. Because of potential disclosure issues, the census industry classification system, while defined in NAICS terms, cannot reflect the full detail for all categories. The industry category, "Public administration," is limited to regular government functions such as legislative, judicial, administrative, and regulatory activities. Other government organizations such as public schools, public hospitals, and bus lines are classified by industry according to the activity in which they are engaged.