The American academic research enterprise relies heavily on contributions made by foreign nationals. Of particular note is the large number of international postdocs employed at universities in the United States (US). Postdocs are among the fastest growing group of academic staff in the US, and over 50 % of all postdocs in the US are temporary visa holders. While academic mobility is sometimes understood using a 'push-pull' model, we argue that demand for educational migrants must be considered. Drawing from Marginson's (Handbook on globalization and higher education. Edward Elger, Northampton, 2011; Marginson and Rhoades in High Educ 43:281-309, 2002) work, we develop a model for assessing local, national, and institutional (or local) variables that may shape the employment of international postdocs at universities in the United States, and we operationalize the model through a panel regression analysis using data covering the period 1989-2009. We find that the passage of time and federally supported research and development expenditures are strong predictors of postdoc employment. Institutional characteristics predict changes only in the subsample of private universities. (HRK / Abstract übernommen).