I think realistically, if camels were introduced into Mexico in the 1600s, I would expect we'd see a world quite different to what I described. I decided to wank California because I got carried away.
But in reality camels would allow for massively expanded trade with Mexico's northern provinces. If we say camels reach Mexico in the 17th century, the over the 1700s many thousands of Mexicans and Europeans would take the passage north into the states of Alta California, Nuevo Mexico and Coahuilay Texas. The key industries there would be ranching, with dates also becoming a staple crop is several key areas. Dates were introduced to Texas and California IOTL in 1765, so I'm not sure they would have made too much of a difference frankly.
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I think while camels will allow greater unity with the rest of Mexico, ultimately the larger populations will be important as they will allow independence to be quicker. Upon Mexican independence in 1820, these provinces will likely be a part of Mexico but by 1830 they would be 3 separate independent states. Importantly, California would have had it's gold rush by this point and so would be a powerhouse in it's own right. Meanwhile Texas and New Mexico would develop as ranching provinces, and later ranching states. IOTL in 1820 the Catholic Church owned a stunning 90% of all settled land in California. New Mexico and Texas would have the same problems, and likely they would reform into a state of landowners by the 1830s.
Generally, Texas and New Mexico, and to a lesser extent California, would be distinct in Latin America due to their huge populations of American settlers who would still move into the area looking for cheap land, but who by 2020 would have largely integrated into the dominant Hispanic culture. I imagine over the 19th century, hundreds of thousands of Europeans would also arrive in Texas and New Mexico, and due to the low population densities I can imagine Europeans becoming the dominant ethnic group in these areas, similar to Argentina and Uruguay.
These areas would also be recognised as independent states rather than being annexed into the US, due to much larger populations by the time 1840 would come around.
By 1930, these states would still generally be weak on the global stage. California would be similar to Argentina in terms of development while I see Texas and New Mexico being more comparable to Chile. However the 1940s would see Texas and New Mexico thrive alongside air conditioning, which would allow for true industrialisation. New Mexico's economy would be dominated by resource extraction and dryland farming, but this would allow for them to achieve a very high standard of living, probably one of the best in Latin America.
So by 2020, I think we would see a California with 60 million people, which would basically be a better Argentina. Due to their proximity to the huge economy of the US, I think they'd fare better than Argentina itself. By 2020 I see a country with a GDP per capita of around $30,000, and a HDI much higher than most of Latin America.
As for New Mexico, I see a republic with 5 million people by 2020, being a hot Spanish New Zealand. Their revenue from mining would allow them to have a GDP of $40,000, similar to the UK and France. I imagine a large share of their population would be immigrants, perhaps around 35% of their population.
I think Texas would have a population of around 18 million people, primarily of European descent. Their large oil supplies would have funded modernisation efforts, and enable them to reach a GDP per capita of $20,000 by 2020 and growing every year.
Overall Texas, California and New Mexico would also be leading destinations for Mexican and Latin American emigrants, who would probably rush into the areas overall.