History example: What was the civil war about? Despite what the southerners claim about "states rights", it really was about slavery. The Confederacy even put it in their declarations of secession, and actually limited states rights in several ways that the US Constitution did not. (example: states could not abolish slavery in their borders!)
Except Texas is very influential when it comes to textbooks. So a lot of them emphasize the states rights thing.
Which answer do I put on the test?