I had assumed that "hi" was a somehow abbreviated form of "hello," but though both of these words appear to have originated from a noise to attract attention, hi actually predates hello. These words both appeared in the mid- to late 1800s, and seem to be primarily American usage. Does anyone know what Americans used for greetings prior to this time period?
Update on 9/10/11:
Although I have come to feel that "how do ye" and its variant "howdy" are most likely the common greetings in the early days of America, part of the difficulty in assessing this is the lack of recorded everyday speech. I was also unaware that "howdy" was used anywhere other than the US South prior to the 1800s, but the OED begs to differ (if someone has the citation for this, please feel free to link it).
There was considerable discussion in chat about the problem of researching common conversational speech, and during the course of that discussion, I realized that probably the best place to look would be plays, since they involve dialogue that might represent a "natural" conversation.
After a lot of searching through early American plays, I came across "holla" used as a greeting in the early American drama The Contrast by Royall Tyler. It was written and performed c. 1759, and its setting is contemporaneous New York City, therefore this greeting is probably an example of natural speech.
Interestingly, I did not find any instances of any other greetings. However, finding plays that were actually set in America in the 1700s and were also written around that period proved difficult.