Why do third parties usually not last very long in the american two party system

For the very reason that us as Americans have been in this two-party system for so long that we would want to keep this tradition rather than to add another party, and oppose eachother even more. Also, voters feel that having a third party vote is irrelevant because it is less likely to be voted for and won over.

i beleive its 1)aids

1.) irish.

2.) settlers could obtain cheap land nearby

3.) steam engine

explanation: