The department Casanare has 19 different districts. You have to choose a specific district to find the ZIP Code
There are 67 ZIP codes in Casanare. There is no Postal Code for all the state. You should navigate to a city (o locality), then for its neighboorhoods to find out the postal code associated with your address. A good way is to use the ¿What is my ZIP Code? tool, that locates the address you are at the moment and based on this geolocation, will show you your ZIP Code Area in Casanare.
To check other states ZIP Code, access Colombia ZIP Code