Conowingo was originally located on the eastern bank of the Susquehanna River at the confluence of the Conowingo Creek with the river. Conowingo was at the rapids that were the first navigation obstacle on the Susquehanna upstream of the Chesapeake Bay, the location of an early stretch of canal. It was also the site of the Conowingo Bridge.
However the 90 foot fall of the river at the rapids dictated the location of the Conowingo Dam and thus the resulting inundation of the original Conowingo site by the subsequent Conowingo Reservoir. At the completion of the dam in 1928, the Conowingo Post Office was relocated to the hill above the dam.
Conowingo is not an incorporated municipality, nor a US Census Bureau designated place.