9/ In many places there are disagreements about which side of the river/water the border is on.
For example between Germany π©πͺ and the Netherlands π³π± at the mouth of the Ems river
https://de.wikipedia.org/wiki/Deutsch-Niederl%C3%A4ndische_Grenzfrage
10/ Sometimes disputes arise because the old methods of surveying the border werenβt very accurate. This can lead to surprises when the border is re-surveyed using more modern technologies, like this example between US πΊπΈ states North and South Carolina.
https://www.cbsnews.com/news/border-redraw-in-the-carolinas-would-mean-19-homes-changing-states/
#geoweirdness