After 1880 the bulk of immigrants going to the U.S. were coming from Europe.
The main way in which the railroads contributed to the end of the large buffalo herds was that "The railroad tracks were obstacles that the buffalo would not cross". It sounds silly, but the buffalo actually refused to cross the tracks for reasons that are still misunderstood.<span />
<span>Numbers of vehicles on road increases tremendously. </span>
The first one is the answer.
A. east of the Mississippi River
