Explanation: it is important for European Union countries to share borders for trading purposes. Since the European Union, countries aim free movement of goods, services and even human capital, having open borders adds to the ease of trading. Similarly, European Union countries offer privileges to the employees providing them the ease of movement between European Union countries offering them jobs. Moreover, the open border facility also reduces disagreements between those countries
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The European Union is essentially Europe's NAFTA, a free trade agreement between all member countries. It has developed a single market between all the members and adopted a unified form a money; the Euro.
Since the Union aims at promoting the free movement of goods, people, services and capital, nations directly connected each other would ideally have open or shared borders to make this process easier. If a union is promoting free trade and movement, the last thing you want is to have checkpoints and borders impeding that movement of goods, people, etc. When you are sharing borders, like America and their states, the movement that you are trying to promote becomes exponentially easier, and arguments or disagreements between member nations on the issue are less likely to occur.
Ice wedges are a big cause of potholes in roads and streets. As ice forms in the cracks of a street, the water expands and pushes against the surrounding rock, making the cracks wider, eventually breaking apart the rock.
