This report details higher education enrollment in South Dakota colleges and universities as of the close of the second week of the 1991 spring term. The tables present data on headcount and full-time equivalent enrollment for public and private institutions; compare 1991 to 1990 figures; and provide data on various categories of students by individual institution. Enrollment is shown in the following ways: by undergraduate degree credits, for special and terminal students, for graduate students by institution, by resident versus non-resident, for resident degree-credit undergraduate students, for resident special/terminal students, for resident graduate students, through resident/non-resident comparison, for resident degree-credit undergraduate students, for resident special/terminal and graduate students, for nonresident degree-credit undergraduate students, for nonresident special/terminal students, for nonresident graduate students, for nonresident degree-credit undergraduate students, and for nonresident special/terminal and graduate students. Resident and nonresident summaries are provided as well, and distribution by undergraduate and graduate categories, new registrants (headcount and full-time equivalent enrollment), student age distribution, student ethnic origin, enrollment by gender, plans of South Dakota high school graduates, and a spring/fall semester comparison summary are also given. The document also contains a list of South Dakota institutions of higher education, and includes historical notes on the evolution of the data collection process since 1973. (JB)