Colonial America bottom line:

British soldiers in (military) highland dress - YES!

Civilians in traditional highland dress, especially post-1746 - NO!

Exception: Oglethorpe's highland immigrants in Georgia, 1730s-40s.

Of course, one can never say "never." You might, PERHAPS, have seen some civilians wearing highland garb in large Scots immigrant enclaves such as that in N. Carolina, though there are no period descriptions supporting this. But, since highland dress was not very adaptable to N. American conditions, the Scots - not being idiots! - would wear clothing that made sense. Even highland soldiers donned britches and leggings in huge numbers. Besides, the fact of the Proscription in the home country would preclude travelling to the New World in traditional dress. Maybe the odd tartan plaid or arisaid functioning as a blanket.

What WOULD be seen amongst New World highlanders: knit bonnets, dirks, perhaps the odd basket-hilt sword. I don't believe any tartan was being woven in the Colonies (except in Nova Scotia), so not many tartan plaids would be in use, except a small surviving number brought from the homeland, which would be used until worn out....