Harvey became a civil engineer and headed west as a prospector to Pike's Peak in 1859 as a Fifty-Niner.

After meeting several discouraged miners along the way, Harvey decided to settle instead in Kansas Territory, so he acquired a plot of land in Riley County near Fort Riley and engaged in agricultural pursuits.

From 1861 to 1864, he served with the Union Army during the Civil War, advancing to the rank of captain in the 4th Kansas Infantry, which failed to complete organization and was consolidated with other recruits to form the 10th Kansas Infantry.

He attained the rank of captain, commanding the 14th Regiment, Kansas State Militia.

After his U.S. Senate term, Harvey worked as a government surveyor in New Mexico, Utah, Nevada, and Oklahoma, before returning to Kansas in 1890 to resume agricultural pursuits.