What is the significance of the 2nd Party System?
The major significances of the Second Party System are that it was based largely on class lines and that it helped to put off the sectional discontents that led to the Civil War.
In general, this was a time in which the Democratic Party was the party of the people. The other party, the Whig Party, was generally the party of business interests. These parties both had strong followings in both the North and the South. This made it so that the sectional animosities were mitigated and did not become strong enough to break the country up for some decades.
The United States has two major political parties because most elections require a majority to win. For example, to become president a candidate must win a majority of the Electoral College, so candidates must try to gain a majority.
In some counties, candidates can gain office with less than a majority, so those countries have more than two major political parties