America Uber Bremen Franco? Huh?

Got this cover in a dollar box because the "America Uber Bremen Franco" intrigued me. I showed it to a dealer friend and he said oh must've been on the Bremen--but that ship that I believe he was referring to didn't come into being until the 1920s. What does this handstamp mean and is this cover, in your educated opinions, worth a buck? Also, what are the back handstamps with the numbers? Receiving marks for Berlin or Hamburg or Bremen or something of the like? I see it in some auction results but what bothers me is they never tell what it means! I don't care what a similar one sold for, I'd like to know WHY it sold for that and what a collector looks for. Teach me more niche stuff c'mon

Definitely worth a buck.

"Bremen" here is the city in Germany. The handstamp shows the routing with Bremen as the transit point. FRANCO indicates that the the cover was prepaid, as does the New York PAID ALL marking. Note the cover is endorsed "Via Hamburg or Bremen". You could choose the routing well before this time, perhaps to catch the earliest ship if you knew that from newspaper reports.

Assuming the docketing at right refers to the original letter enclosed (see sender's note at left), then this is a cover from 1868. This makes it one handled by the newly created Northern German Confederation's postal union that pretty much consolidated all the different states' rates together into one bag (with 2 different currencies, though).

The backstamps are from Berlin, dated 23 January. Good service!

Thanks for such a thorough and enlightening answer! Cheers to you

James van der Linden's book Catalogue des Marques des Passages lists this AMERICA ÜBER BREMEN FRANCO mark as known from 1854 in red.

It was applied in Bremen to mail received from the US and my guess is that this is from an earlier date than the manuscript one at the right at a time when Bremen was still an independent state.

There were quite a few AMERICA ÜBER BREMEN and AMERIKA ÜBER BREMEN marks in use at different times and the ones from the 1860s had the AMERIKA spelling and the text in a double circle, although I guess this could have been an old handstamp that was still in use.

Edit: Corrected spelling of AMERICA - Thanks oldboldandbrash

"America" or "Amerika"?

https://www.rumseyauctions.com/auctions/lot/75/508