Is transit visa needed for trip EWR-Delhi-Shanghai-ORD?

Dear Sir/Madam,

I'm an US citizen and will be on a business trip from Newwark, US to Delhi, India. On my way back to US, I would like to visit Nanjing/Jiangsu, China for 5 days. Do I need a transit G type if I fly from Delhi to Shanghai then take the train from Shanghai to Nanjing? I plan to also take the train back from Nanjing to Shanghai then fly back to Chicago US. Thanks so much!
Best,
Vivian