But it is true they aren’t making land anymore. And, in fact, farmland prices have done better than home prices over the last century as well as in the worst years for housing, the years bracketing the recent financial crisis. Real farm property values actually rose 21 percent over the full financial crisis, that is, between 2006 and 2012. For farmland, there was only a small 3 percent drop in real price from 2008 to 2009, which was quickly reversed.

Don’t get too excited. They aren’t making land, but because of technological advances collectively called the Green Revolution, there has been something akin to a long-term supply increase. This 20th-century miracle in agricultural science greatly improved crop yields per acre. From the standpoint of farm output, there was no need for new land. This revolution involved the discovery by Fritz Haber of a cheap process to produce ammonia for fertilizer at the beginning of the century and the discovery of new high-yield strains of wheat by Norman E. Borlaug at midcentury. Both men won Nobel Prizes for their work. These innovations permitted multiplication of yields per acre and very likely saved hundreds of millions of lives from starvation worldwide.

The effects of this revolution are complicated. One might think that progress that improves yield per acre would put upward pressure on land prices. But that is not necessarily so, if it occurs globally and prevents food price increases that would otherwise earn farmers more revenue.

What’s more, the food revolution may be accelerating with changes like lab-produced milk from genetically modified yeast and lab-produced meat from stem cells, eliminating the need for livestock and their pasture. This could have deleterious effects on farmland prices.

Of course, underneath every home is a piece of land. Although that is typically only a bit of former farmland, it is often in an urban or suburban area, where a plot of land tends to cost much more than in the country.

Sometimes that little piece of land dominates the value of the home, particularly in dense urban areas. But if we are to understand long-term trends, we need to realize what land represents, even in Manhattan or Silicon Valley or any booming area. People in such places usually aren’t buying land for its own sake but for the myriad services that housing provides. A home is not just a place to sleep and store clothing and keepsakes. It can be a place that is convenient to a stimulating place of work, good schools and entertainment and, indeed, part of an entire human community.

These services have developed enormously over the last 100 years, changing the spatial and geographic dimensions of housing. There are vastly more highways and automobiles, telephones and various electronic connections, enabling people to leave center cities and still obtain the housing services they want. Thus, from a long-term perspective, these developments relieved a great deal of the upward pressure on home prices in cities.