During the 1800s there was still lots of land that didn’t really have any real owners people had claimed it but it wasn’t really their’s because people were still fighting over land so it was not safe to call anything yours at that time and just like everyone else the US was trying to get as much land as possible and the US came out on top and Mexico just didn’t after that Mexico was out raged and demanded that we give them Texas because we had taken California from them and that started The Mexican US war which lasted from 1846 to 1848
