This is a Gold Mine--and I mean that in the literal sense. It's very easy to get lost in this labyrinth and sometimes difficult to find your way back, but oh, there are some real nuggets here.
These are link pages created by the El Centro College of Dallas, Texas to give students further reading in the History 1301 (to 1877)and History 1302 (after 1877) classes. The courses focus on Texas, but cover much of American history and culture. Below I've put in links to the useful pages for the 19th century.
Industrial Age to 1877 / Civil War / Reconstruction / The Year 1877 / Late 19th Century /
The South 1877-1900 / The West to 1900 / Native American / African American
There are all sorts of links here to numerous to list. Go ahead and explore.