I was able to visit the El Paso Museum of History on the same night that I visited the El Paso Museum of Art. The two museums are located literally right next door to each other. Thus, you can easily visit both museums on the same day.
The El Paso Museum of History does a nice job of telling the story of the El Paso-Juarez region. Interestingly enough, one of the major focuses of the museum is the concept of transportation. I did not expect the museum to be so focused on transportation but it actually makes sense given the fact that El Paso is in a region that has been an important thoroughfare across the mountains.
The El Paso-Juarez region was known as El Paso Del Norte - the pass of the North, due to the fact that the Rio Grande River provides a natural pass through the mountains. In addition, the main road from Mexico City to Santa Fe ran through El Paso-Juarez. Today, Interstate 10 carries traffic between Southern California and Florida and all points in between. It runs right through the heart of El Paso. Given all these facts, the emphasis on transportation is quite logical.
El Paso-Juarez is a fascinating place, and this Museum will give you a nice introduction to it.