Nathaniel Bradstreet Shurtleff Sr. (June 22, 1810 – October 17, 1874) was an American politician, serving as the twentieth mayor of Boston, Massachusetts from January 6, 1868, to January 2, 1871.^[4]

Nathaniel Bradstreet Shurtleff Sr. was born on June 22, 1810, in Boston. His father was Benjamin Shurtleff, a physician.^[5]

He was initially educated in the Boston Public Schools system but later transferred to the short lived Round Hill School in Northampton. After graduating, he attended Harvard Medical School and followed his father's footsteps in becoming a physician.^[5]

He was a member of the Harvard Board of Overseers.^[5]

Shurtleff, who had been defeated as the Know Nothing candidate for mayor in 1855 and as a Democrat in 1865 and 1866, was elected in 1867 as a Democrat.^[6] He won re-election in both 1868 and 1869.

Shurtleff was largely unaware how to run a city; and thus, struggled as mayor. During his mayoralty Atlantic Avenue was laid out, Federal Street was widened, and other streets were extended. The task of laying out streets was transferred from the Board of Aldermen to a board of commissioners during his mayoralty. The city also gained ownership of the East Boston ferries and annexed Dorchester while he was mayor.^[5][7]

Shurtleff did not run for a fourth term in the 1870 election.

He died on October 17, 1874, at the age of 64.^[8]

Shurtleff was elected a member of the American Antiquarian Society in 1849.^[9] He was chosen to serve on the society's board of councilors from 1853 to 1874.^[10] In 1857, he was elected to the American Philosophical Society.^[11]

Shurtleff is well known to genealogists and historians as the editor of the Massachusetts Bay Colony records (published in five volumes from 1853 as Records of the Governor and Company of the Massachusetts Bay in New England) and of part of the Plymouth Colony records.

• A Topographical and Historical Description of Boston.

• Timeline of Boston, 1860s-1870s