What was the general view of major American Christian denominations prior to that point?
EDIT: I ask this in reference to the belief by some modern fundamentalist sects that the Earth is 6,500 years old, and that this knowledge reflects a long-known Christian truth.
So, this belief is something known as Young Earth Creationism, which, according to it's doctrine, believes (as you stated) that the world is about 6,000 years old or younger (some claiming it's as young as only 5000 years old). Belief in this type of thinking is actually a rather modern, which became perpetuated in the United States during debates over creationism vs evolution which gripped America for the better part of the 20th Century. The HBO Documentary Questioning Darwin actually does a pretty great job summarizing some of the conflicts between the two sides during this time period.
Young Earth creationists claim that they know the age of the Earth based off math of the various ages of people in the bible. A good example of this can be found here. The obvious problem for this (and the reason why different groups report different numbers) is because A) There is no accounting for ages for many characters in the bible between various prophets, especially after King David dies, and B) Historically, there's very little evidence that most of the characters in the "Old" Testament actual existed, mainly referring to Abraham and other characters whose age is attested too in the document.
Truth be told, the Old Testament is meant more to be taken allegorically, not literally, but when American Evangelical Christians felt that their faith was under attack due to the rise of Darwinian Evolution, they turned to studying the ages of the Old Testament in order to counter with their own answer.
Archbishop Ussher of Armagh, back in 1658, took the Genesis lists of descent, the begats, and figured...
" In the beginning God created Heaven and Earth, Gen. 1, v. 1. Which beginning of time, according to our Chronologie, fell upon the entrance of the night preceding the twenty third day of Octob[er] in the year of the Julian [Period] 710. The year before Christ 4004. The Julian Period 710."
From this all the others derive, adjusting more or less for various reasons. Various Christians coming to the New World brought it with them. From 1701 the date was normally an annotation in the King James Bible.
It required the development of historical geology for it to be challenged.