Traveling the Oregon Trail generally took about six months. Traveling to Oregon by sea took twice as long, up to about a year.
The Oregon Trail began at Missouri River spots such as Kansas City, Missouri or Independence, Missouri. The trail itself was about 2,000 miles long.
There's no seaport in the central United States where the Oregon Trail began. So taking a sea route from that area would have meant river travel out to the Gulf of Mexico and then all the way around South America and back up the coast to reach Oregon. Similarly, anyone leaving from the East Coast by sea would have to travel all the way south around South America and back up again to the western coast of North America.
So, as arduous as the Oregon Trail was, it was a better route than the sea route.
Travel by sea took over a year. One had to travel all the way down past Cape Horn, the southern tip of South America. The overland route on the Oregon Trail only took about 6 months. Remember that the travel wasn't non-stop. Settlers often stopped and built cabins and raised crops to make more money for supplies to continue the journey.
