Because it is difficult to measure in the population, there is only general agreement on how many people have mental retardation. While estimates of the percent in the U.S. population range from .67% to 3%, the most accepted estimates find approximately 1% of the noninstitutionalized population has mental retardation. This translates to about 2.5 million noninstitutionalized people having mental retardation. Estimates vary by age and definition used.
Additionally, in 1995, there were an estimated 346,659 people with mental retardation in residential settings and institutions: 33,943 are in nursing homes; 62,028 are in state institutions; 37,311 reside in private institutions with 16 or more residents; and 213,377 live in other community facilities. Another estimated 1,400 persons with mental retardation are in the non-mental retardation/developmental disabilities units of psychiatric hospitals.
In 1995, there were an estimated 1.3 million people of all ages reporting mental retardation as a cause of activity limitation (NHIS). People, age 15 and over, reporting mental retardation as a cause of disability in the SIPP in 1992 totaled 501,000.
Source: LaPlante 1995; McNeil 1993; Prouty and Lakin, 1996
Survey: NHIS, 1992; SIPP, 1992