Pressure on emergency medical services (EMS) is rising. The growth in EMS utilization has coincided with a decline in the number of emergency departments (ED). Between 1994 and 2004, the annual number of ED visits in the United States rose by 18 percent (from 93 million to 110 million) whereas the number of hospitals operating 24-hour EDs decreased by 12 percent during the same time frame. This study has three objectives: (1) analysis of diversion trends, (2) effect of ED staffing, capacity and financial characteristics on ED diversion hours and (3) effect of changes in ED access on mortality rates. For the first objective, we employ descriptive statistics to study ED diversion trends. For the second analysis, we use a two-part model to study the effect of hospital staffing, capacity and financial characteristics on diversion hours. For the third objective, we use simple ordinary least squares and fixed effects techniques to determine the effect of ED access on mortality rates. In particular, we examine two measures of ED access: diversion hours (a temporary change in ED access) and distance to closest ED (a permanent change in ED access). We find statewide ED diversion impact of California in 2005 to be 11 percent. This means hospital EDs in California in 2005 were on diversion status 11 percent of the time. Reducing the number of nurses increases the number of hours an ED is on diversion status. Interestingly, increasing the number of intern or student doctors in a hospital increases the number of hours an ED is on diversion status. For heart-related and cancer-related deaths, we find a positive correlation between distance and mortality rates. However, for diversion hours, we find it counterintuitive that increasing diversion hours reduces mortality rates. Further study will need to be done to verify this finding.