http://www.newyorker.com/online/blogs/elements/2013/10/why-abraham-lincoln-loved-infographics.html
As a consequence of the way our brains perceive our surroundings, we humans are visual creatures with a knack for finding patterns (sometimes even where they don't exist, hence conspiracy theories!). It's easy to see why infographics would appeal to those of us trying to make sense of large amounts of information, like leaders considering their constituencies and commanders looking over battlefields. I'd wager that infographics first came about in the late 1700s not because of any lack of interest in the format, but rather because it was significantly more difficult to gather the data necessary to populate them! Once there were more reliable and timely reports of populations, troop movements, &c., it seems inevitable that somebody would have had the notion to display the information in a visually succinct fashion.
The Civil War, by virtue of its chronological place in history, was the first major American engagement after the advent of proper infographics; it stands to reason that Lincoln would have been delighted with this useful new instrument at his disposal. It's also worthwhile to note that the Union Army would have been leaps and bounds ahead of the Confederates in its ability to gather the type of data best suited to infographics. Not only did the North have access to decades of records, it also had by far more extensive postal and transportation systems. Lincoln's maps and charts would have been significantly more comprehensive than what Jefferson Davis had.
Lincoln's extremely detailed slave population map
These days, we have precisely the opposite problem. Information is much easier to come by -- so much so that we're constantly inundated by facts and figures in the news. Infographics have become, rather than a tool for aggregation, a tool for selection and analysis. (This is, of course, aided by technologies unfathomable in Lincoln's time.) We like charts and graphs because they speak to that ancient part of our brains that latches onto patterns, turning the night sky into constellations and the landscape into mythology. They shape a flood of information into a cohesive narrative -- and narrative is essential to how humans define who we are and how we fit into this universe.
As they say, a picture is worth a thousand words.
