If I want a tee shirt, I just hop in a vehicle, go to a store and buy one.
Not so on the Oregon Trail in the 1840s when the largest number of people went west on it.
Cotton is a natural fiber and it is grown in fields. I mention this because now there are synthetic fabrics word and they don’t grow in a field.

I’ll start with the maps. All of the images are from Wikipedia Commons.

Oregon Trail Map  by, National Park Service

NASA topographical map with the trail drawn by Matthew Trump.

Picture of a covered wagon by Larry D. Parks.

These are two pictures of cotton in fields. From the USDA.

Here is a picture of cotton for sale as a fiber, not thread or clothing. By, Flora de algodonFrobles.

This is a cotton mill. Raw cotton goes here to be processed. From the New York Public Library.

These are bobbins of cotton by, Talent.

Spinning with the bobbins. From the Library of Congress.

Cotton jins. By, e NOSH from USA.

A spool of spun cotton by, Streckband.

The last two pictures show different thread weights. By, Durova. In the second picture, there is an US quarter to show the sizes.