Reuben came to Buffalo in 1810 with Abel Moore Grosvenor, with whom he opened a store on Main Street called Grosvenor and Heacock. After Abel died in 1813, his brother, Seth, took over his interest in G. & H. When Seth left for New York City in 1816, the youngest Grosvenor, Stephen K. took over Seth's position.
On 02 Jan 1816 Reuben was appointed to serve on a committee to plan the building of a new harbor for the city. Later, Reuben Heacock, Samuel Wilkeson, Albert H. Tracy and Oliver Forward offered to build a canal to Buffalo for $30,000 ($65,000 cheaper than the Black Rock Plan). In 1827 Reuben and his Buffalo Hydraulics Association built the Hydraulic Canal, tapping the Buffalo River near Gardenville and bringing water four miles to the junction of Seneca and Swan streets. By 1832, six mills were in operation there.
"Municipality of Buffalo, A History", Buffalo & Erie County Historical Society