Although Richard has not been found in the 1850 census, there is a listing in Saint Paul, Ramsey County, Minnesota Territory in that year for the family of an Edward McLagan, age 22, b. Louisiana, who may have been a brother.
In the 1860 US Census for White Bear, Ramsey County, Minnesota the Family of Richard McLagan was enumerated within another family group, as follows:
Dwelling #2535; Family #2292
Wm. Still, 29, M, Mate, Real property $200, Personal property $100, b. Ohio, Person over 20 years of age who cannot read or write
Emily Still, 23, F, b. Illinois
Mary E. Still, 8, F, b. Minnesota
Charles H. Stiles, 6, M, b. Minnesota
Nancy Stiles, 3, F, b. Minnesota
Augustus Stiles, 1, M, b. Minnesota
Richard McLagan, 28, M, Clerk, b. Louisiana
Mary McLagan, 22, F, b. Ohio
Julia McLagan, 6, F, b. Minnesota
Olive McLagan, 4, F, b. Minnesota
Georgiana McLagan, 1, F, b. Minnesota
Richard enlisted in the Union Army on 16 Oct 1861 and was assigned to the Fourth Minnesota Infantry, Company "G" as a private. He was discharged on 21 Dec 1864, also as a private. He was divorced from Mary (Barnum) McLagan on 1 Oct 1870 in Saint Paul, Ramsey, Minnesota (copy of divorce decree). He married Mary Victoria Young McMillan on 18 Feb 1871 in Saint Paul (copy of the marriage certificate and license). He died 27 April 1894 in Saint Paul and was buried in the Episcopal Cemetery, White Bear Lake, Ramsey, Minnesota (from civil war pension rolls).