There are nearly 80 main story missions in Red Dead Redemption 2.
Things to Do First in RDR2 - Everything you need when you're getting started.Note that main missions unlock all sorts of things like Fishing, Fences, and Camp Upgrades. The Red Dead Redemption 2 chapters break up the main story missions, and this guide is broken up similarly. IGN's Red Dead Redemption 2 (RDR2) walkthrough features guides for every main story mission, complete with Gold Medal Checklist Requirements, helpful screenshots, and tips for each of them.