The late nineteenth-early twentieth century saw

The late nineteenth-early twentieth century saw: the rise and dominance of the Republican party
The republican party, tend to value things such as strong military, strong borders, and less government involvement in the economy. During that development time, all of these things are very valuable since the country has to face threats from all sides of the world.

The median is 4 because 2 x’s out 9, 3 x’s out 7, 3 x’s out 5, and 4 is the only remaining number.