Help With Identification Of Stampless Cover

Hi, I'm hoping someone here can help me identify more about this cover. I believe it's US, as it was with a few other US covers, but I suppose it could be British. It is dated 1805 multiple times within the letter content, and is a response to some form of financial dealing (there is also an account balance and ledger on a further fold-out page of the main letter). The script within is large and flowery, but surprisingly more legible than a lot of other 19th century script I have seen. I could not identify any wording that gives away the location, nor read the signature. I cannot discern the destination in the letter nor the red marking; just the name it was sent to and the "paid" script in the top corner. Thanks for any help.

Edit: Spelling

Neither, it is Scotland in a place called Leith.
Near Edinburgh

Isn't that a purty cover? MMMmmmm!

Thanks so much for your help! :) You were able to identify in a few seconds something that had me scratching my head all day; Scottish postal history definitely isn't something that I have any knowledge of. I have a few other stamps/covers that have had me stumped in the past that I'll likely be picking the brains of the members here with in the near future. The knowledge here definitely does not disappoint. Again, thank you!

You will let yourself down if you leave it there,
try taking covers like this until you
get a dead end.
You will never know what you will find.

I'd suggest the recipient of this cover
is a prominent Whaler of Leith and he owned
at least one ship.
He was a merchant, and his youngest daughter Jane
married another Merchant John Hutton in 1824

We have a member here, Eunice Shanahan, a brilliant philatelist
who reads stampless covers like yours, but she
only drops in infrequently.
Try Googling her name and you will find her
web address and letters she has put under the micrsoscope.

Your postmark is smudged and I cannot advise
what it would have been.

Cheers.

Rod's advice to continue to pursue is spot on. I've been doing the same with stampless letters from the U.S. and it is amazing what one is able to find these days online.

If you're interested in what the addressee of your letter looked like, check out this link: http://www.europeana.eu/portal/reco...46FA73B.html

As to the postmark, are there any indications in the letter content as to where it was written (and by extension likely sent from)?

Great work Tomisek!
with pre stamp covers, I think one can generally
assume a strong genealogy result, because people
using the post at this time were educated and wealthy.