Because production must take place in physical space, a land factor must normally be present. In rare cases, land may not be scarce and therefore is not technically a factor. For instance, in centuries past the site of productive activity might have been a ship at sea; in such an instance, the ship (a capital good) served a role similar to land. (Today, sea lanes are scarce and the ocean itself can be considered a factor of production in such cases.) Analogously, a spacecraft might substitute for land as a production site in our own century.

In addition to land or an equivalent capital good, production requires a labor factor. In general, therefore, at least two (scarce) factors are always required.