As I’ve documented before, sizable racial attitude change has occurred among Democrats in the liberal direction over the last 5-10 years. An unsettled aspect of this development, though, is how much the 2016 election (elites, campaign messages, etc.) drove the racial liberalization as opposed to preceding forces (e.g., activism around racial issues). A quick review of some racial attitude survey data here can produce a rough answer to this question.
Panel survey data can isolate individual level change (actual changing of minds) on racial attitudes. The 2010-2014 Cooperative Congressional Election Study panel and 2011-16 Voter Study Group panel have two common racial resentment (RR) items that can shed light on attitude change during a span of years that does include the last election and thus can capture factors from the 2016 election environment (2011-2016) and another span of years that does not (2010-2014). The obvious caveat in comparing individual level racial attitude change across these two datasets is that these are two different surveys with different people, so results should be treated as suggestive (though the data does come from the same vendor, YouGov, offering some reassurance).
Two graphs below visualize individual level change from 2010-2014 and from 2011-2016. Similar to what I’ve done before, the first graph (Figure 1) breaks down 2014 RR responses by 2010 responses, and the second graph (Figure 2) breaks down 2016 RR responses by 2011 responses. The key portion of the graphs to pay attention to is the percentage of original non-racial liberals (most importantly, those taking a conservative position) changing to a liberal opinion on each item and how this varies by time span.

On the “overcome” RR item (left-hand side) in Figure 1, 12 percent of original racial conservatives change to the liberal position between 2010 and 2014. In terms of the survey responses, this represents a change from agreeing that blacks should overcome prejudice without special favors (a racially conservative stance) to disagreeing with this sentiment (a liberal stance). Importantly, this racial position switch outweighs the mirror opposite as only six percent of original racial liberals change to a conservative position (change in the liberal direction does not get cancelled out by opposite movement). However, as the below Figure 2 graph shows for the same item (left-hand side), a greater amount of original conservatives (21 percent) switch to the liberal side on this RR item 2011 to 2016–a time span that includes any influence from the 2016 election. Greater movement in liberal direction for those originally indifferent (Neither/DK) for 2011-16 compared to 2010-14 occurs too.

Similar results appear for the “slavery” RR item shown on the right-hand side of Figures 1 and 2. On this question, 20 percent of original racial conservatives–disagreeing that generations of slavery/discrimination have made it difficult for blacks to work their way up–became racially liberal (agreeing with the statement) four years later in 2014. Once again, while greater than the opposite movement (only seven percent of racial liberals became conservative), the trend towards more racially liberal attitudes is greater for the time span that includes 2016. 30 percent of original racial conservatives (in 2011) adopt racially liberal attitudes on this RR item five years later, a greater percentage than the one seen for the 2010-14 change.
In sum, the data here shows that some individual level racial attitude change was already developing prior to the 2016 election. It’s also worth clarifying that for all of these comparisons of percentages, the 2011-16 span essentially covers the 2010-14 span and thus this former time span picks up most of any pre-2016 election racial attitude change. Given these time frames and the fact that these are different surveys, it remains difficult to clearly discern when the change occurs most. Nevertheless, a time frame that includes 2016–and thus likely any influence from the last election–clearly contributes at the very least some amount to the racial attitude change seen within the last decade.