From such estimates, however, combined with the censuses of hearths, peculiarly unsatisfactory in Spain as they excluded the privileged classes and were, as their violent fluctuations show, carelessly made, we may arrive at the conclusion that in 1557 the population of Spain was barely 9,000,000.
More difficult, if possible, is it to measure the amount of the decline in the latter half of the century.

[Sidenote: Decline] It was widely noticed and commented on by contemporaries, who attributed it in part to the increase in sheep-farming (as in England) and in part to emigration to America.

There were doubtless other more important and more obscure causes, namely the increasing rivalry in both commerce and industry of the north of Europe and the consequent decay of Spain's means of livelihood.

The emigration amounted on the average to perhaps 4000 per annum throughout the century.

The total Spanish population of America was reckoned by Velasco in 1574 at 30,500 households, or 152,500 souls.