In The Manhattan Beach March (1893), we are obliged to settle for an internal cadence (dominant ending for the first strain).
In Our Flirtation March (1880), an equally stark ascending line from ^5 to ^8 closes the second strain. I am quoting here from an early 20th century theater orchestra set of parts. In such circumstances, the violinist was considered the leader. In the second strain, the flute part duplicates the upper notes of the violin's octave, the first cornet and first clarinet the lower notes.
Combined with the melody, the circled notes would create what I call a "wedge," two voices approaching the final tonic from opposite directions. Historically, the more common version has a descending line above and a rising line below, but here Sousa does the opposite. We are obliged to imagine the final tonic note in the descending line ^5-^4-^3-^2- (^1). I have examined the full band score for this march and no part makes a ^2-^1 descent.