TY  - JOUR
AU  - Ellison,Glenn
AU  - Glaeser,Edward L.
TI  - Geographic Concentration in U.S. Manufacturing Industries: A Dartboard  Approach
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 4840
PY  - 1994
Y2  - August 1994
UR  - http://www.nber.org/papers/w4840
L1  - http://www.nber.org/papers/w4840.pdf
N1  - Author contact info:
Glenn Ellison
Department of Economics
Massachusetts Institute of Technology
50 Memorial Drive, E52-380A
Cambridge, MA 02142-1347
Tel: 617/253-8702
Fax: 617/253-1330
E-Mail: gellison@mit.edu

Edward L. Glaeser
Department of Economics
315A Littauer Center
Harvard University
Cambridge, MA 02138
Tel: 617/495-0575
Fax: 617/495-7730
E-Mail: eglaeser@harvard.edu
AB  - This paper discusses the prevalence of Silicon Valley-style localizations of individual manufacturing industries in the United States.  Several models in which firms choose locations by throwing darts at a map are used to test whether the degree of localization is greater than would be expected to arise randomly and to motivate a new index of geographic concentration.  The proposed index controls for differences in the size distribution of plants and for differences in the size of the geographic areas for which data is available.   As a consequence, comparisons of the degree of geographic concentration across industries can be made with more confidence.  We reaffirm previous observations in finding that almost all industries are localized, although the degree of localization appears to be slight in about half of the industries in our sample.  We explore the nature of agglomerative forces in describing patterns of concentration, the geographic scope of localization, and the extent to which agglomerations involve plants in similar as opposed to identical industries.
ER  -