This will help you find your answer.
The first expeditions using the Oregon Trail were in 1839-1841 and in 1846 the route became passable for wagons all the way to the Willamette Valley in Oregon. After about 1865 the Oregon and California trails got shorter and shorter as the Union Pacific railroad went west and the California based Central Pacific railroad went east, until they met at Ogden, Utah in 1869. Use of the Oregon and California trails rapidly declined after that. And of course towns were founded at each station of the transcontinental railroad.
So the Oregon Trail was used for emigration to Oregon for about 20 to 30 years, and the California Trail for a similar length of time.
Mormon settlers followed the California Trail partway to California and founded Utah in 1847 when it was still technically in Mexico. Settlers on the California Trail often bought supplies from the Mormon settlements in Utah on their way to California. So Utah is a famous example of a settlement founded part way to the west coast, although the Mormons never intended to go all the way to California.
The trading post known as Bent's Old Fort, used from 1833-1849, was for much of that time:
. . . the only major white American permanent settlement on the Santa Fe Trail between Missouri and the Mexican settlements Wikipedia:Bent's Old Fort National Historic Site
The fur trading post and later army base of Fort Hall, Idaho, just to the east of where the Oregon and California trails diverged, was an important stop on the trails and a place where immigrants could get repairs and resupply. And Fort Bridger, Wyoming was also a vital resupply point on the Oregon trail.
And it is easy to imagine that small settlements may have developed at places like Fort Hall and Fort Bridger to supply and service the immigrants on the Oregon Trail.
The Overland Stage, the Pony Express, and the Transcontinental Telegraph line all needed regularly spaced stations along their routes, and small communities developed at some of those stations.
So if you can find old maps, guidebooks, and descriptions of the Oregon Trail from the 1860s, shortly before it became discontinued, it is probable that you will find mention of a number of small settlements along the route.