Chiang Mai - Kunming - Detroit (via Shanghai)

Hi I'm flying to Kunming from Chiang Mai on the night of Dec 25 and flying to the US the morning of Dec 26. I'll only be in Kunming for 2.5 days and I have tickets and to and from two different countries. However, my flight to the US from KMG has a short layover in Shanghai. Will I still be able to sightsee in Kunming without a visa? Thanks!