Population density is an issue, for sure. Santa Cruz, for example, has a population density of about 1.3 people per square kilometer. It's actually the second largest province by area, (~244K sq km), with a relatively small population of only 333K people.
La Pampa and Chubut are both just over 2.5 people per sq km. CABA, by extreme contrast, has a population density of well over 15K people per sq km
If you're really interested, there's a nice page at-
https://en.wikipedia.org/wiki/Provinces_of_Argentina
If you hit PageDown three times, there's a chart of the 23 provinces plus CABA, with seven clickable/sortable columns, so you can sort by area or population or density, etc