What was the most direct result of the Gold Rush on California's population in the late 1840s?

The population grew extremely quickly in a short time.

The population decreased as people moved to find gold elsewhere.

The population stayed about the same but became wealthier.

Only people from the eastern United States moved there.

What service was established to solve the problem of slow mail delivery to and from California?

The first cross-country railroad

A single rider rode a horse all the way across the country.

Mail was carried by a series of riders on horseback.

Letters were sent using coded messages over wires.

Mail was transported in large, protected wagon trains.

The creation of the Pony Express.

California achieving statehood.