The 2016 U.S. presidential election results surprised many, after several groups many believed to be surefire voters for Democrats based on previous elections voted for Republican Donald Trump (Bump, 2016). Whenever a change takes place in voter patterns, one begins to hear phrases like “critical election” and “political realignment.” A critical election is an election where there is a change of at least 10 percent in partisan alignment, but it does not persist in the next election. A partisan realignment is similar to a critical election, but the change is more durable. This research explores whether the 2016 election can be classified as a critical election and whether and how key groupings of Democratic voters voted in the election compared to their votes in the 2012 election. Using data aggregated at the county level, regression analyses suggest that voters’ education, access to health care, union membership, racial/ethnic diversity, and income level all had statistically significant relationships with votes in both elections and with the change in vote between 2016 and 2012, all were substantively significant or in directions consistent with the presence of a critical election when viewed either from the national or even regional viewpoint. Evidence suggests that 2016 was a critical election. / M.A. / If 2016 proved anything about elections, it is that at times they can be difficult to predict. Predicting voter behavior based on past elections is not straightforward, in part because at times voters can make sharp changes in their party alliance over the course of four years. Sometimes those changes are lasting, but they also can fade by the next election cycle. This study examined whether the 2016 U.S. presidential election constituted such a sharp and sudden change from the 2012 election, an event social scientists term a “critical election.” Conducted at the county level, the study examined whether and how voter groupings (based on education, access to health care, union membership, income, and race/ethnicity) changed notably between 2012 and 2016. What was found was that as expected Democrats experienced a negative change in support among union, white, and impoverished voters. What was not expected was the negative change in Black votes for Democrats between 2012 and 2016. Another unexpected, though smaller, change was a drop in Democratic support by the college educated. No significant change in Democratic support was found among Hispanics or those with access to healthcare. Based on these findings 2016 can be considered to have been a critical election for Blacks.