Here are some of the boundaries around the world and each one they are following in different way.
PAKISTAN & CHINA
HOLAND & BELGIUM
SPAIN & PORTUGAL
ENGLAND & SCOTLAND
LAOS, MYANMAR & THAILAND
ALGIERS & MOROCCO
GERMANY & CZECH
SPAIN & FRANCE
PAKISTAN & INDIA
MEXICO & USA
CANADA & USA
PARAGUAY, ARGENTINA & BRAZIL
FOUR US STATE
AFTER WAR BOSNIA & CROATIA
PAKISTAN & CHINA
US & CUBA
ITALIA & FRANCE
MALAYSIA & INDONISIA
SOUTH & NORTH KOREA
NEBRASKA & EVA
NEPAL & INDIA
UZBAKISTAN & TAJECKTAN
SAUDIA & YEMEN
NORWAY & SWEDEN
TURKEY & GREECE