In the first hand account which detail does the author includes show that the pony express was important to everyone in Sacramento

The pony express was important to everyone because it linked the eat to the west.

Explanation:

The pony express was the first rapid transit rail and the first mail line in the whole continent. It was a first of it's kind experience for all the people living in that continent. The pony express also marked the highest development of land travel before the arrival of the Pacific rail road.

The first hand account that was used by the author that showed how and why the pony express was important for all the people in Sacramento was that it linked the western region with the eastern region. It was a huge achievement of physical resistance of man and horse.