Traveling to Philippines

I am heading to the Philippines In end of April .. I am an American Citizen who will go from the US by bus to Toronto , where I will catch a Plane from Toronto and land in Shanghai. My Layover in Shanghai is 24hrs exactly.. Do I need to get a China visa for this layover or would i be able to get the 72 hour or 144 hour free transit ?? if so , how do I do this so I have no issues before I arrive in China for this layover? before heading to the Philippines?!