1. The boundary between Maryland and Pennsylvania; symbolic dividing line between North and South before the American Civil War
   - Mason-Dixon line, Mason and Dixon's line

Type of: state boundary, state line

• genus Loxia
• genus Loxodonta
• genus Loxoma
• genus Loxostege
• genus Lucilia
• genus Lufengpithecus
• genus Luffa
• genus Lumpenus
• genus Lunaria
• genus Lunda
• genus Lupinus
• genus Luscinia
• genus Lutjanus
• genus Lutra
• genus Luvarus
• genus Lycaena
• genus Lycaeon
• genus Lychnis
• genus Lycium
• genus Lycoperdon
• genus Lycopersicon
• genus Lycopersicum
• genus Lycopodium
• genus Lycopus
• genus Lycosa