Petroleum County Library 205 S Broadway S Winnett, MT 59087 Phone : (406) 429-2451 Business Category Libraries Petroleum County Of--community Library Winnett, MT 59087 Phone : (406) 429-2451 Business Category Government Offices-County Libraries Government Offices & Public Schools Petroleum County-winnett--library Winnett, MT 59087 Phone : (406) 429-2451 Business Category Government Offices-County Libraries Government Offices & Public Schools