BKK-CAN (Guangzhou Baiyun Airport) -WUH-SFO

Hello, I have not gotten a clear answer from China Southern Airlines nor the Chinese Embassy. I am flying from BKK to Guangzhou with a six-hour layover then Guangzhou to San Francisco with a "stopover" in Wuhan for 1 hour 20 minutes. I am on a US Passport. Do I need to get a visa before I leave or am I good with the 24-hour free transit visa? Any help would be greatly appreciated.