Answer:
Historically, innovations in travel led to westward expansion in the United States.
Transportation and communication have served to unify United States citizens.
Explanation:
Hello. You did not show the text to which this question refers. However, in researching your question, I was able to find a question exactly the same as yours that showed the text. This text is in the figure attached below.
According to the text, we can see how the establishment of transportation stimulated communication and unification and expansion in the USA. This makes transportation an extremely beneficial and positive innovation for the country, being able to facilitate the daily lives of citizens and to strengthen national ties, in addition to allowing territorial expansion through the travels that developed the western USA.