Mineral wealth? But fertile fields- probably. Although they did find "oil" later.

http://en.wikipedia.org/wiki/1860_United_States_presidential_election

The 1860 Republican National Convention in Chicago nominated Lincoln, a moderate former one-term Whig Representative from Illinois. Its platform promised not to interfere with slavery in the South but opposed extension of slavery into the territories. The 1860 Democratic National Convention adjourned in Charleston, South Carolina, without agreeing on a nominee, but a second convention in Baltimore, Maryland, nominated Illinois Senator Stephen A. Douglas. Douglas's support for the concept of popular sovereignty, which called for each territory's settlers to decide locally on the status of slavery, alienated many radical pro-slavery Southern Democrats, who wanted the territories, and perhaps other lands, open to slavery. With President Buchanan's support, Southern Democrats held their own convention, nominating Vice President John C. Breckinridge of Kentucky. The 1860 Constitutional Union Convention nominated a ticket led by former Tennessee Senator John Bell.

Lincoln's main opponent in the North was Douglas, who won the popular vote in two states, Missouri and New Jersey. In the South, Bell won three states and Breckinridge swept the remaining 11. Lincoln's election motivated seven Southern states, all voting for Breckinridge, to secede before the inauguration and the secession of four more, including two that voted for Bell, after Lincoln mobilized Federal troops to protect Federal property and coerce the seven initially seceding states. The election was the first of six consecutive Republican victories.

It's interesting that in 1850 there were 23,191,876 people in the US (not sure if slaves were included) and the same size as Australia (but more arable). Farm mechanization didn't appear till the 20th century from my limited research. In the 1850's it appears that without slavery the view was that labour supplies would be the limiting factor to growth- and a sudden change in (labour/slave) policy would disadvantage investments in agriculture which was actually reducing food prices and suffering- even slaves would be disadvantaged- the US was a big exporter- so changes in the labour supply would effect world food prices.

http://www.u-s-history.com/pages/h980.html
http://www.greatachievements.org/?id=3783

I wonder what the African's in Africa were doing to increase the availability of food in the 1850's- I suspect that the Afro-American's were doing much better. Even white peasant's had it pretty bad in the 1850's without mass manufacturing- especially in Britain's climate. Perhaps by investment, work, planning, thinking Britain was able to grow despite it's weaknesses in the 1600-1700's by founding colonies in climates favourable to growing crops on a larger scale.

All very interesting, but it’s got nowt to do with Lincoln being like Putin..

Canem, in the 1850 they were just climbing out of the Little Ice Age and Europe had had about 50 years of hard cold times.
Crop yields I imaging would have started increasing.
I wonder where one would find info on crop yields for 1700 to 1900 ?