Which of these is the most common characteristic of a political map? identification of cities, states, and countries
presence of topography and boundaries
labels for continents and oceans
key for natural resources

The correct alternative is "Identification of cities, states and countries".

A political map must have states and countries marked on it, also its capitals. But on the other hand, there's no need for the presence of topography and boundaries, because it would include the political boundaries, not the natural ones.

Also, labels for continents and oceans is not a characteristic of a political map, nor the key for natural resources.

do you have a list of sources to choose from?

in the 1800s, locomotives powered by steam made transportation faster and cheaper. the resulting rapid growth of railroads led to the connection of the atlantic and pacific railroad in oklahoma city in 1897.

in the last years of the century, the improvement of steam-based engines the expansion and growth of railroads. this growth increased when the companies started to build and expand, such as the atlantic and pacific railroad, which connected new mexico with california, and missouri with oklahoma. many of these new networks were built in oklahoma, and these changes transportation henceforward.