One book that takes place in every UN member state, plus the two observer states (Palestine and the Holy See), as well as the following non-sovereign states or nations: 

Puerto Rico 
Hong Kong
Wales 
Northern Ireland 
England 
Scotland 
Greenland 
Bermuda 
First Nations of the USA 
Catalonia 
Quebec
Corsica
Sicily 
Tibet 
Taiwan 
Kosovo 
Antarctica 
Svalbard