USD meaning in Medical ?

A unified school district (in the states of Arizona, California, Kansas and Oregon) or unit school district (in Illinois), in the United States of America, is a school district that generally includes and operates both primary schools (kindergarten through middle school or junior high) and high schools (grades 9–12) under the same district control.

This distinction is predominant in states where elementary school districts and high school districts are, or were, generally separate. The Los Angeles Unified School District is a major example of a unified school district in California. In Illinois, unit school districts must not be confused with consolidated or union school districts, which are generally formed by the consolidation of multiple school districts of the same type.

In Kansas, the unified school districts developed after legislation passed in 1962 that was intended to reduce the number of rural school districts. After the law's passage, the number of districts in Kansas dropped dramatically. In 1947, there were over 3,000 districts. After the unification law and establishment of unified school districts, their number dropped to under 400.

In Arizona, unified school districts elect 5 school board members. Common school districts have elected boards consisting of 3 members.