What we know
Larkspur's predecessor. PO from March 24, 1860; reopened Jan. 22, 1862 under D. C. Oakes; closed Aug. 29, 1867; reopened under Crull April 8, 1869; renamed Larkspur Dec. 13, 1871, when the office moved to the railroad. Hiram P. Bennet's 1862 application says an older Huntsville two miles west had been abandoned after a failed water mill (Larkspur Historical Society binder 4 p. 408, via a digest; not yet).
Where it was
Center of Sec. 16, T9S R67W: the post office site report signed by William Crull, May 1869, gives 'Huntsville … Section No. 16, in Township nine' south, nearest creek 'Plum', Monument 12 miles southerly (Larkspur Historical Society binder 1 p. 58, OCR; the range is illegible in the OCR). Good to about half a mile. The 1866 survey puts a road, the People's Fort and a sawmill on the south line of Sec. 16 (Pierce, Larkspur Historical Society binder 1 p. 120); local accounts put Huntsville 'at the clay pits, two miles north of Larkspur' (Larkspur Historical Society binder 1 pp. 20, 24, via a helper's digest).
Placed from a written description, such as a land section, a distance from a landmark or an old survey note.
Sources
Sources are named in the text above. Numbers such as S-0080 refer to our source list. Most newspaper quotations were read in the Colorado Historic Newspapers Collection. Long quotations from recent books are shortened here.