Yes,
there were 
several.
During Thomas Jefferson’s tenure as Ambassador to France and then
as Secretary of State, he sought men and means to explore what would
eventually become the Louisiana Purchase. Some of the plans were simply
silly, such as the proposed John Ledyard expedition, others had real
potential, such as John Sinclair’s and George Rogers Clark’s
proposed trips. In the end, none of them got beyond St. Louis (Sinclair)
and the rest never got off the ground.
At the same time as the Lewis and Clark expedition was sent to explore
the northern reaches of the Louisiana Purchase, the Hunter and Dunbar
group went south to ascertain the location of America’s southern
boundaries. Like their more famous counterparts, Hunter and Dunbar were
also to collect samples of flora and fauna, but mostly to engage in
map-making.
Immediately after the return of the Corps of Discovery, General James
Wilkinson, commander of American military forces in the trans-Appalachian
West, sent Zebulon Pike to find the headwaters of the Mississippi. In
1809, Pike was sent west again, this time to trace the Arkansas and
Red Rivers. It was during this time that he discovered the mountain
that today bears his name. Unfortunately, the Spanish found Pike and
arrested him, returning him to Mexico until his release some months
later.
