Going to Thailand via china do I need transit visa for CAN(5hr) and URC(2hr) holding usa passport?

I have round trip flight with layovers in URC and CAN. The max time is 5 hours in CAN and 2 hours in URC I need a transit visa or is a 24 hour transit apply?

Austria to Thailand
Stopovers China

Ürümqi Diwopu International Airport URC
China Southern
2 h 0 m layover

Guangzhou Baiyun International Airport CAN
China Southern
5 h 10 m layover

Returning flight
Thailand to Austria

Guangzhou Baiyun International Airport CAN
China Southern
3 h 25 m layover

Ürümqi Diwopu International Airport URC
China Southern
1 h 55 m layover