West of St Lewy. I have bartered for a couple shirts and pants with lining to be made. So basically fur trade era working my way to the mountains of Colorado. I’m within spitting distance of the Oregon trail / Santa Fe trail and one of Sublett’s crossings
Cord was a working mans clothing, however it was very popular with officers at sea, naval and merchant. It was wider then today’s but I don’t know how it compares to wide wale cord you can find today. It was very popular in England.
“In 1847,me corduroy britches I put on, me corduroy britches I put on and went working on the rail road, the rail road”
I don't think broad or narrow fall trousers would be more appropriate for a fur trade persona than the narrow button fly trousers as seen at the link above. There probably was quite a mix of styles. A man leaving home on the farm in Missouri to head to the mounts to seek his fortune would have left home wearing his plowing clothes, which could have been any style.
Back when I was in a club and putting together clothing for a persona, I went for a button up fly. I was working on the persona of a discharged dragoon from Fort Scott heading towards Taos and the fur trade of the southern Rockies. As far as I could learn dragoon issue trousers were made with a button fly.