What effects did the reform impulse in the pre-Civil War era have on American socio-cultural identity?
There are many possible ways to answer this. I would argue that the most important effect of reform movements like the temperance movement was to strengthen the idea that the United States was something of a utopian country. Part of our socio-cultural identity is that we are a country in which we are never satisfied with the way things are. We are not willing to settle. Instead, we want everything to be perfect. You can argue that this part of identity came out of (or at least was strengthened by) the Second Great Awakening and the reform movements that it inspired.