The letter from Swain details to his wife Sabrina the progress they have made on their journey and the events of recent times. The opening topic is that of a celebratory dinner (although the occasion is not specified) rather than how he is keeping or his concern for family, etc. Swain is highly unemotional at this point, simply complaining about postal services of his letters.
The surprise of good luck on their trip shows that they are familiar with death on similar activities or know of such stories. With this in mind, it shows the dominating American desire to explore and colonise also. Yet the motives of their trip are not revealed in this letter particularly, so could just be doing this to expand American ideologies and belief systems across the continent or extend their nation's power and exceptional mind-set.
This is clearly a trip of an exploration of some sort and so his singular paragraph on the actual landscape is entirely monosyllabic and descriptively simplistic with no value judgements or mention of what he as a human individual thinks of what he is seeing. What is surprising also is that there is no mention of potential animals, wildlife - other than two plants - or even Native Americans that they might (or might not as that would also be of interest to travellers) have seen. This might be explained by the typical American belief of the time that the West was essentially empty and desolate.
After this, he becomes more emotional about missing his home and family. He even becomes slightly poetic on the line 'I should long for the time to come
when I shall turn my footsteps homeward' but seemingly disregards them and turns his focus back to the mission at hand. However his affection overules at the end as he is certain of his eventual return - 'when I get home I will kiss you all.'