My Grandmth, Margaret Estella LARMAN-LEWIS-LAWLOR b. o1/1900, and listed on the 1900 fed census taken in Washington DC, which can be found at www.ancestry.com
(She was still "un-named" infant on 1900 census'), , had a "maternal Grandmother who's "maiden" name was JOHNSON, we also, had JOHNSTON'S, in the family, also Mary's in DC/VA area's.
My Grandmother's first husband was a Joseph Irvin LEWIS, b. DC 1894, one of his "Maternal" Grandmother's was a Mary E. JOHNSON, (listed in Washington Post at her death in 1940's DC).
My father's Howard Irving LEWIS' faternal Grandmother was a Mary E. JOHNSON-LEWIS, who he remember's fondly.
Mary E. JOHNSON-LEWIS', father was a Joseph JOHNSON,(b. 1847) was was a messenger in 1880 and may very well have lived on Florida Ave., I'll have to check further, John H. LEWIS, helped build Florida Ave., Washington DC.