I am flying from Chicago to Kathmandu and have flight changes in Shanghai and Kunming

I am US citizen, do I need a Visa?

Itinenary
China Eastern Airlines Flight 718 Boeing 777-300
2:50p
Chicago, IL
ORD O'Hare Intl Airport
6:25p
Shanghai, China
PVG Shanghai Pudong Intl Airport
14h 35m Economy
Layover in Shanghai, China (PVG)
2h 40m
MU
China Eastern Airlines Flight 748 Boeing 737-800
9:05p
Shanghai, China
PVG Shanghai Pudong Intl Airport
12:20a
Kunming, China
KMG Kunming Changshui International Airport
3h 15m Economy
Layover in Kunming, China (KMG)
14h 5m
MU
China Eastern Airlines Flight 757 Boeing 737
2:25p
Kunming, China
KMG Kunming Changshui International Airport
3:35p
Kathmandu, Nepal
KTM Tribhuvan Intl Airport
3h 25m Econo