Complex sentence: The Denver & Rio Grande railroad building west toward Grand Junction reached Montrose later in 1882 and Montrose became an important regional shipping center with a branch railroad line serving the mineral rich San Juan Mountains to the south.
Split into simpler sentences: The Denver & Rio Grande railroad building west toward Grand Junction reached Montrose later in 1882, and the town became an important regional shipping center. A branch railroad line served the mineral-rich San Juan Mountains to the south.