Immigrants have disproportionate lack of access to healthcare and insurance. Emergency departments could serve as a healthcare substitute and increased demand can negatively affect the US emergency services system. Medical Expenditures Panel Survey (2000-2008) data was modeled to compare emergency departments (ED) use between non-citizens, foreign-born (naturalized), and US-born citizens. Group differences were assessed using non-linear decomposition techniques. Non-citizens were less likely to use ED services (8.7 %) compared to naturalized immigrants (10.6 %) and US-born Americans (14.7 %). Differences in ED use persisted after adjusting for the Behavioral Model covariates. Healthcare need and insurance partially explained the differences in ED use between the groups. Between 2000 and 2008 non-citizen immigrants used markedly less ED services compared to US citizens, regardless of their nation of origin. We also found that demographic and healthcare need profiles contributed to the divergence in use patterns between groups. A less restrictive healthcare policy environment can potentially contribute to lower population disease burden and greater efficiencies in the US health care system.