One of the most important decisions to make when teaching 19th century US history is how you want to frame it. Traditional framings tend to ignore or downplay the presence of Native Americans.
You might like to explore a couple of Twitter threads I've written on framing.
If you have a bit more time, then I have a longer CPD session in video form. In this video I explore different ways US history has been framed by historians and textbooks and why we really need to re-think. This was originally done as a series for A Level / GCSE students but is equally applicable for teachers.
In this SHP Understanding session historians tackle the issue of how we teach about conflict between Native Americans and US colonisits during the 1860s and 1870s. Lots of useful bits here to bring you up to date with recent historiography.
In this video I explore three stories which show how Indigenous peoples resisted and survived US expansion and attempted genocide. These stories cover the period 1868-1940. This is imporant as many books tend to stop in 1890 with the assumption that Native Americans ceased to exist. Many of these stories would work really well in teaching GCSE American West and conintued Native presence.
This video explores the contemporary issue of missing and murdered Indigenous women and traces the historical roots of the issue. This really helps with framing the importance of studying C19th US history.