This paper explores the manifestations of regional governance in South
ern California. The author evaluates whether three regional public aut
horities, empowered to address areawide transportation and air quality
constraints, fragment or integrate regional identity and vision. He e
xamines the lessons of the Southern California experience for other US
regions engaged in government reorganization. He argues that Southern
California regionalism constitutes a shadow governance characterized
by technical bias, single purpose compartmentalization, and institutio
nal insularity. He concludes that the affiliation of regional planning
with single purpose and systems maintenance functions has facilitated
regionalism at the same time it has limited its potential by function
ally fragmenting and submerging the regional public interest.