Looking at Colorado, since the 30s we've always been in the low-mid-40% born in the state, everyone else being an immigrant. California (cough) is our biggest source of origin currently, around 6% of the population, Texas coming in next with around 3%. "Colorado remains one of the most diverse states in terms of domestic migration;" the majority of states have a majority native-born population.
Where We Came From, State by State
Charts showing how Americans have moved between states for 112 years.