▁titled ▁Mad ▁City ▁Ch ick ens ▁was ▁made ▁about ▁their ▁campaign . ▁More ▁and ▁more ▁cities ▁that ▁had ▁previously ▁b anned ▁urban ▁ch ick ens ▁are ▁removing ▁old ▁reg ulations ▁or ▁making ▁perm its ▁easier ▁to ▁obtain . ▁ ▁Pol ic ies ▁toward ▁keeping ▁ch ick ens ▁vary ▁by ▁country , ▁county , ▁or ▁city . ▁Other ▁cities ▁with ▁urban ▁ch icken ▁programs ▁and ▁activ ists ▁include ▁Hal if ax , ▁New ▁York ▁City , ▁Port land , ▁Oregon , ▁Seattle ▁and ▁V ancouver . ▁ ▁In ▁the ▁UK , ▁the ▁keeping ▁of ▁ch ick ens ▁has ▁also ▁grown ▁in ▁popular ity ▁with ▁as ▁many ▁as ▁ 2 0 0 , 0 0 0 ▁households ▁involved . ▁ ▁Sales ▁of ▁the ▁fashion able ▁E gl u ▁hen ▁house ▁increased ▁ten - fold ▁between ▁ 2 0 0 4 ▁and ▁ 2 0 0 9 . ▁ ▁Com mer cial ▁vs . ▁back yard ▁egg ▁production ▁Com mer cial ▁egg ▁production ▁has ▁been ▁associated ▁with ▁sal mon ella ▁and ▁other ▁disease ▁out break s ▁in ▁the ▁United ▁States . ▁Po or ▁san itation ▁and ▁crow ded ▁hen ▁houses ▁have ▁contributed ▁to ▁these ▁problems . ▁Exp ansion ▁of ▁the ▁p oul try ▁industry , ▁fue led ▁by ▁an ▁increased ▁demand ▁for ▁p oul try ▁products , ▁has ▁created ▁a ▁demand ▁for ▁high ▁throughout ▁p oul try ▁and ▁egg ▁production . ▁The ▁resulting ▁increased ▁p oul try ▁population ▁density ▁and ▁the ▁re aring ▁ ▁of ▁in compatible ▁p oul try ▁species ▁in ▁close ▁proxim ity ▁have