Most of McLellan's poems are nature-focused, many highlight the unique aspects of American culture: the frontier, Native Americans, and hunting for moose and bison. He set poems in the plains of Illinois, in the Wyoming territory, along the coast of Florida, and in parts of Canada. More exotic poems featured elephant hunts in Africa. Amid all of it, he often had a more philosophical message. From the opening stanzas of "Mount Auburn" (1843):
What is Life? — a bubble dancing
On the sparkling fountain's brim,
Painted by the sunbeam glancing
O'er its evanescent rim.
Soon its soft reflected glories,
Images of colored skies,
Vanish — when the haze of evening
O'er the panorama dies.
Life, with all its bliss and troubles,
Melts like unsubstantial bubbles!
What is life? — a little journey,
Ending ere 't is well begun;
'Tis a gay disastrous tourney,
Where a mingled tilt is ran;
And the head that wears a crown
'Neath the meanest lance goes down.
Walk, then, on life's pathway, mortal!
With a pure and steadfast heart;
So that through death's frowning portal,
Peacefully thou may'st depart!