The state poll averages in key states of Wisconsin, Michigan and Pennsylvania prior to the election pointed to a Clinton win in each state. Trump won each state (albeit apparently by a very narrow margin in Michigan). The final RealClear Politics average in Pennsylvania was Clinton +1.9. Trump won by 1.2. From a statistical perspective, this difference between poll average and outcome is within the margin of error. In Michigan, the final polling average was Clinton +3.4, and Trump at this point has a very small 0.3 average win. Wisconsin showed the biggest deviation, with the final poll average of a 6.5 Clinton win; Trump won by 1.0. But the four polls used in the Wisconsin average by RealClear Politics were completed on Oct. 27, Oct. 31, Nov. 1 and Nov. 2. The election was Nov. 8, meaning that the predictions in Wisconsin were based on data about a week or more old.
In Florida, a rich electoral vote prize state, the final RCP average was Trump +0.2. Trump won by 1.3. This was a quite accurate prediction. In North Carolina, the final RCP average was Trump +1.0. Trump won by 3.8. Again, within the margin of error.