External Commuting as a Prelude to Suburbanization

External commuting capitalizes upon existing investment in areas with a deficit in local employment. The Newcastle, New South Wales, commutershed has long included an expanding zone of external commuting in former mining towns well in advance of suburban spread. For displaced miners, and for other autochthonous commuters, strong constraints on residential mobility raise travel tolerance levels beyond those acceptable to suburbanites and other allochthonous commuters. Among external commuters, spatial differences in residential utility and paired residential-workplace utility lead to differing responses to enforced commuting, enabling prediction of the future roles of settlements as commuter source areas. The present structure contains the seeds of change, either toward integration in the suburban zone or toward progressive decline in resident workforce and ultimate disintegration.