Final answer:
Lewis and Clark may have separated to cover more territory, gather more information, or as a tactical decision to ensure the journey's successful completion and to maximize their exploration results.
Step-by-step explanation:
During their historic expedition, Lewis and Clark faced immense challenges and hazards, which included harsh environmental conditions, encounters with wildlife, and the need for ample supplies and information from native tribes. On their return journey to St. Louis after reaching the Pacific Ocean, Lewis and Clark may have separated for a stretch to explore different areas, gather more information, or perhaps to increase the chances of making it back with the valuable data they had collected. Splitting their party could also have been a tactical decision, allowing them to map more territory and potentially establish additional contacts with Native American tribes. Unfortunately, as Lewis met a premature end some years after their return without completing a comprehensive account of their journey, the reasons for specific decisions along their trail are left to speculation and interpretation based on their journals and historical context.