He established the architectural firm Hallock & Company with contractor William McMillan.

Hallock also designed and built homes for many prominent early Oregonians, including Cyrus Olney and Captain George Flanders.

[2] In 1863, Hallock was appointed city surveyor, and established and laid out grades for the streets in Downtown.

He surveyed and mapped many parts of the city, as well as the townsite of Astoria, Oregon.

[3] Hallock married Mary Tiffany Bliss on April 22, 1855.