If a public school can accommodate more students the school board may admit without the payment of tuition persons twenty - one years of age and over, who have school residence in the district. Source: SDC 1939, § 15.3004; SL 1955, ch 41 , ch 12, § 1; SDC Supp 1960, § 15.3001; SL 1975, ch 128 , § 187.