Simplify the following text for a Grade 9 native English-speaking person.
Original: It was the Democratic Party political machine that played a major role in controlling New York City politics and helping immigrants , most notably the Irish , rise up in American politics from the 1790s to the 1960s .
Simplified: It was the Democratic political machine that played a major role in controlling New York City politics . It also helped many immigrants , especially the Irish , rise up in American politics from the 1790s to the 1960s .