* Artificial Borders: Established through human-made markers, such as straight lines ([[Canada–United States border (49th parallel)]]), fences ([[Mexico–United States border]]), or walls ([[Berlin Wall]] - historical). | * Artificial Borders: Established through human-made markers, such as straight lines ([[Canada–United States border (49th parallel)]]), fences ([[Mexico–United States border]]), or walls ([[Berlin Wall]] - historical). |