Notes:
It is unclear whether Samuel had married another daughter of Catherine Alter who had died by the 1850 census and then he possibly married her sister, Ameila in 1855. I have an a marriage date of 20 Dec 1847 in Washington county for Samuel and Ann Alter which I believe came from the Washington County marriage records.
1850 Census MD, Washington Co., District #1, 24 August, p. 234
Cath. Alter, 56, $18,000 real estate, b. MD
Amelia Alter, 27, F, MD
David Alter, 38, M, Farmer, MD, farmer
Ann M. Alter, 23, F, MD <=========== Ann Marie Mumma, wife of David Alter
Saml. Mumma, 27, M, MD, farmer
Ann C. Mumma, 1, F, MD
Sophia Watts, 14, F, MD
Henry Dunmore, 19, M, MD
1860 Census, MD, Washington Co., Boonsboro District, 5th August, Boonbboro PO
Samuel Mumma, 36, druggist, $1200 real estate, $2500 personal, b. MD
Amelia " , 36, b. MD
Annie " , 11, b. MD
John E. " , 4, b. MD
1870 Census, MD, Washington Co., Boonsboro Dist, 2nd June, Boonsboro PO
Mumma, Samuel, 45, retail merchant dry goods, $100 real estate, $4000 personal, b. MD
" , Amelia, 48, keeping house, b. MD
" , John E., 15, at home, b. MD
1880 Census Place: Boonsboro, Washington, Maryland
Source: FHL Film 1254516 National Archives Film T9-0516 Page 168D
Relation Sex Marr Race Age Birthplace
Samuel MUMMA Self M M W 55 MD
Occ: Grocer Fa: MD Mo: MD
A. Amelia MUMMA Wife F M W 57 MD
Occ: Keeping House Fa: MD Mo: MD