There is a problem of aggregation and recency bias when it comes to discussing the political implications of the rapidly growing US Latinx population. Discussions are often saturated by immigration, criminal, and/or economic frames. But rarely have discussions centered on the lengthy history that Latinx subgroups have had in the US, nor have they centered on their positive contributions to American democracy. In my dissertation, I take a historically informed approach to analyze how Mexican-Americans managed to overcome 19th and 20th century authoritarian institutions in Texas, and in effect, initiated a transition to democracy in south Texas.I frame the political transformation of Texas as a form of localized regime change spearheaded by Mexican-Americans seeking the guarantee of democratic protections and political inclusion. I develop this argument by analyzing the distinct settlement patterns between Anglo and Mexican-American populations in north and south Texas. I identify historical processes that structured Anglo-Mexican relations along a top-down racial hierarchy as contact and southern Anglo migration increased throughout the state. I tracethe unique geopolitical history of Texas, first as a newly independent republic and later as a US state, to demonstrate how few democratic protections were afforded to Mexican-Americans and other Latinx subgroups throughout the state.My dissertation demonstrates how, despite the presence of various authoritarian institutions, Mexican-Americans managed to organize their limited resources to capitalize on key internal and external political opportunities. The implications of my dissertation are far reaching. First, it provides a cautionary tale to political parties, pundits, and observers on the limits of demographic determinism. A large and/or rapidly growing Latinx population is not a guaranteed formula for political change. Second, it provides a transferable rubric for Latinx communities throughout the nation seeking to transform their local and state political systems. Finally, it demonstrates how investing in communities and local level politics may be the solution to safeguard American democracy from state and national level democratic backsliding.