So you think matching up GTAIV, GTASA and RDR gives a good estimate inThe size of the map
I think the GTASA scale is a bit off here though
haha, good visualization, but too amny changes to estimate.
RDR is not a 1;1 overlay on San Andreas, same with Liberty City. RDR made good use of the entire map, very effective use, but you were traveling on a horse which traveled a fraction of speed of vehicles in SA and GTAIV. Also, there were a fraction of routes available. Even in San Andreas, you could take 5 or 6 possible routes from one city/town to another, with open high ways and tight winding roads... the travel could take anywhere from 10 minutes to cross from a city, all the way to an 30 minutes or more if you took backroads. GTA4 was different in that there were no highways to travel from one area to another, so going from one side of the map to the other still took about 6 minutes I'd estimate.
It took much longer in RDR to cross from, say, Tall Trees to Presido, but that was because of your vehicle and your path. And if you made a diversion to any town along the way, it could double that travel time.
But, RDR wasn't really THAT large. But, because of travel constraints, pacing, scale, and effective environmental effects, it made the world feel like one of Rockstar's largest. Arguably, I think that San Andreas hits the mark for being largest. GTA4 had a huge amount of variation on your travel path, but, IMO, you spent 90% of your time on 8 or 10 roads.
Said, in a sentence: RDR is much smaller than GTA4 and SA, but feels larger. SA is probably the largest.