How did the United States policies change or evolve over time ? Politically, Economically or Socially. (pick one aspect and show the American change over time)

It has a clear purpose and thesis or controlling idea. 

The thesis is supported with adequate reasons and evidence. 

It shows sustained analysis and critical thought. 

It is organized clearly and logically. 

It shows knowledge of conventions of standard written English. 

It shows awareness of disciplinary conventions in regards to content, style, form, and delivery method.