Jefferson County Voter Rgstrtn 729 Maple St Hillsboro, MO 63050 Phone : (636) 797-5486 Business Category Government Offices-County Legislative Bodies Jefferson County Of--courthouse, Voter Registration Hillsboro, MO 63050 Phone : (636) 797-5486 Business Category Government Offices-County Miscellaneous Personal Services Voter Registration County Government-Courts Courts Government Offices & Public Schools