; ▁many ▁people ▁have ▁em igr ated ▁to ▁larger ▁cities ▁and ▁regions ▁outside ▁the ▁province , ▁such ▁as ▁Lab ourd , ▁Bé arn ▁and ▁Paris . ▁In ▁the ▁last ▁century , ▁Sou le ▁has ▁lost ▁more ▁than ▁three ▁qu arters ▁of ▁its ▁population , ▁which ▁has ▁caused ▁the ▁need ▁for ▁different ▁municipal ities ▁to ▁be ▁merged ▁in ▁order ▁to ▁ass ure ▁the ▁maintenance ▁of ▁public ▁services . ▁ ▁L arg est ▁cities ▁ ▁Administr ative ▁divisions ▁▁ ▁Trad itionally , ▁Sou le ▁has ▁been ▁divided ▁into ▁three ▁ge ographical ▁regions , ▁each ▁of ▁which ▁group ▁a ▁determin ate ▁number ▁of ▁municipal ities ▁or ▁communes . ▁ ▁P ett ar ra , ▁compr ising ▁the ▁lower ▁Sou le , ▁in ▁the ▁north . ▁It ▁includes ▁the ▁towns ▁and ▁villages ▁of ▁Ain h arp , ▁Ar ou e - I th or ots - O l ha ï by , ▁Ber rog ain - Lar uns , ▁D ome z ain - Ber ra ute , ▁Esp ès - Und ure in , ▁Et char ry , ▁Gest as , ▁L ' H ô p ital - Saint - B la ise , ▁L oh itz un - O y her c q , ▁Ma ul éon - L ich ar re , ▁Mon c ay ol le - L arr ory - M end ib ieu , ▁Os ser ain - R iv are y te , ▁V iod os - A ben se - de - Bas . ▁Ar b ail a ,