The discovery was made around 2:00 p.m. in the area of 3rd and Reaney streets.
Police say the device had wires attached.
When the device could not be identified, the area was cordoned off and several nearby homes were evacuated for precautionary measures.
The Delco Bomb Squad responded and made the device safe.
Officials say the device was on private property but, as a precaution, trains slowed down in the area because the device was only 50 yards from the railroad tracks.
Chester Police, along with the ATF, are investigating.