During the period in which America was being colonized, writings of the Colonial Period and the Puritan Period were popular. The writings of this period included themes of an instructive nature and were, typically, religious in nature.
The first typical form of writing during these periods was the sermon. Perhaps the most known sermon produced at this time was Jonathon Edward's sermon Sinners in the Hands of an Angry God. This sermon, essentially, was intended to place fear in his congregation in order to force them to wake up to the power and wrath of God.
The second typical form of writing during this period was personal diaries. One famous diary from this period was Samuel Sewall. His Diary has come to be recognized as one which influenced many writers to come. (On a side note, Sewall was one of the judges during the Salem Witch Trials.)
One last form of writing popular during this period was the personal narrative. Many personal narratives during this period gained popularity. One of the famous narratives of the time was The Sovereignty and Goodness of God, also known as A Narrative of the Captivity and Removes of Mrs. Mary Rowlandson.