Prior to the Civil War the US federal government's means of income were tariffs and excise taxes on things like whiskey. How did the US government actually collect that money? Was the US treasury department in charge of it? Did they send men out to farm and ports across the nation to inspect things coming and collect the necessary due?
I know there have been previous discussions here on what the US taxed, but I've not seen if others have talked about how.
In Before passage of the 16th Amendment and enactment of a federal income tax, what taxes did the federal government levy?, I wrote a lot about the process for the 1813 direct tax, including assessors, assistant assessors, collectors, returns, and such. However, direct taxes were generally assessed only in the early US.