First of all, not everyone would agree that the election of 1896 was the most important since 1860. There are those who would argue that the election of 1876 was just as important. The election of 1876 was important mainly because it caused the end of Reconstruction.
However, if we start from the assumption that the election of 1896 was the more important, then we must say that it was important because it marked the end of rural populism as a truly important force in American politics. In the years up to 1896, the populists and their demands had figured prominently in American politics. There was an intense battle going on between the rural, agrarian, populists and interests based in the cities. By 1896, however, America was becoming much more urban. This was reflected in the election. McKinley’s defeat of William Jennings Bryan put an end to the debates over free silver and the gold standard. It showed that the balance of power in American politics had shifted from the countryside to the cities.