Parker eventually found more stable ground in a position with the New York City Police Department, where he served for years as a superintendent of buildings and as a member of various administrative capacities.

The work was not glamorous, but it was steady, and it allowed Parker to support his family — he had married Minnie Orton Sackett in 1867, and they had a daughter, Maud, born in 1869 — in reasonable comfort in a city that offered professional opportunities unavailable in more rural environments.

He remained engaged with questions of Native American affairs from outside the government.

He corresponded with journalists, historians, and reformers who were interested in the history of the Haudenosaunee and the contemporary situation of Native Americans.