The main reason why the US joined the war was because multiple attack on passenger and merchant ships with submarine attacks .The final straw was when the RMS Lusitania by a German u-boat going to Liverpool England .
Answer:
Edward R. Murrow work against McCarthy
Please give a time frame for this question
but I will still say that the answer is:
<span>The major cause of the growth of the workforce was an increase in immigrants.</span>