▁She ff ield ▁and ▁Michigan . ▁ ▁Linear ▁cart og rams ▁▁ ▁While ▁an ▁area ▁cart ogram ▁manip ul ates ▁the ▁area ▁of ▁a ▁polygon ▁feature , ▁a ▁linear ▁cart ogram ▁manip ul ates ▁linear ▁distance ▁on ▁a ▁line ▁feature . ▁The ▁spatial ▁dist ort ion ▁allows ▁the ▁map ▁reader ▁to ▁easily ▁visual ize ▁int ang ible ▁concepts ▁such ▁as ▁travel ▁time ▁and ▁connect ivity ▁on ▁a ▁network . ▁Dist ance ▁cart og rams ▁are ▁also ▁useful ▁for ▁comparing ▁such ▁concepts ▁among ▁different ▁ge ographic ▁features . ▁A ▁distance ▁cart ogram ▁may ▁also ▁be ▁called ▁a ▁central - point ▁cart ogram . ▁ ▁A ▁common ▁use ▁of ▁distance ▁cart og rams ▁is ▁to ▁show ▁the ▁relative ▁travel ▁times ▁and ▁directions ▁from ▁vertices ▁in ▁a ▁network . ▁For ▁example , ▁on ▁a ▁distance ▁cart ogram ▁showing ▁travel ▁time ▁between ▁cities , ▁the ▁less ▁time ▁required ▁to ▁get ▁from ▁one ▁city ▁to ▁another , ▁the ▁shorter ▁the ▁distance ▁on ▁the ▁cart ogram ▁will ▁be . ▁When ▁it ▁takes ▁a ▁longer ▁time ▁to ▁travel ▁between ▁two ▁cities , ▁they ▁will ▁be ▁shown ▁as ▁further ▁apart ▁in ▁the ▁cart ogram , ▁even ▁if ▁they ▁are ▁phys ically ▁close ▁together . ▁▁ ▁Dist ance ▁cart og rams ▁are ▁also ▁used ▁to ▁show ▁connect ivity . ▁This ▁is ▁common ▁on ▁sub way ▁and ▁met ro ▁maps , ▁where ▁stations ▁and ▁stops ▁are ▁shown ▁as ▁being ▁the ▁same ▁distance ▁apart ▁on ▁the ▁map ▁even ▁though ▁the ▁true ▁distance ▁var ies . ▁ ▁Though ▁the ▁exact ▁time ▁and ▁distance ▁from ▁one