To my Brazilian friends: I apologize if you find my understanding of Brazilian politics of the 1930s superficial.  It's very difficult for anyone outside a country to really understand the dynamics of politics inside that country.  I don’t intend any insult or condescension to anything Brazilian in anything I say here.

What actually happened: In the late 1920's Britain tried to go back on the gold standard after leaving it during World War I.  They priced gold too low relative to the pound and ended up draining themselves of much of their gold reserves.  That threatened the world with financial instability.  Financial institutions in the US increased the US money supply to help settle things down.  The extra money flowed into the US stock market, where it fueled a stock bubbled centered on new technology like television, which was just starting to look practical.

The US stock market collapsed on October 29, 1929.  That didn't immediately put the world in the Great Depression.  For quite some time--nearly three years in some countries--economic life went on in a fairly normal way.  Even in the US, most companies and individuals went on about their businesses as though nothing important had changed for months or even a year after the crash.  In the mid-term election of 1930 Republicans lost some seats in congress, and ultimately lost control of the House of Representatives, but the balance was very close.  For a while in 1930 it looked like the world economy was going to weather the storm and start expanding again.

The economic disruptions kept coming though.  The end of World War I had left Central and Eastern Europe full of small, economically weak, and often poorly run countries.  As the world economy weakened, reduced demand for agricultural products devastated the region.  The Central Bank of Austria collapsed in spite of efforts by the other central banks of Europe, especially the British, to prop it up.  The Austrian collapse led to a cascade of collapses throughout Europe.  Those collapses eventually reached Britain.  France held out for a time, then got hit extremely hard in 1932.

As confidence in the banking system evaporated, bank runs became common.  People lost confidence in their banks and rushed to pull money out.  The impact reverberated through economies.  Banks were forced to keep more money on hand, which meant that they had to pull loans from otherwise healthy farms and businesses, often forcing those farms and businesses into bankruptcy.  At that point the Great Depression was on in earnest.

As the depression got worse, governments made matters worse by cutting off imports in an effort to save local jobs.  That led to a cycle of retaliations.

The historic wild card: Laid-off people who had lost their savings looked desperately for a way out.  Some turned to radical ideologies.  Others bit on schemes promoted by con artists who sold everything from the location of Francis Drake's mythical treasure to pyramid schemes, and to shares in oil wells where there was no oil to be had.  One con artist named Columbus (Dad) Joiner set off the next economic disruption in October 1930 by actually finding oil with what was apparently supposed to be essentially a stage prop oil drilling operation.  He didn’t just find oil.  He found the giant East Texas oil fields—largest in the US at the time--in an area where the major oil companies were sure there was no oil to be found.  Historically that set off an oil stampede, with thousands of wildcatters drilling for and often finding oil.

The oil stampede produced winners and losers.  Demand for oil was low because of the depression, and the huge new supply pushed prices down to ridiculously low levels--from nearly $2 per barrel down to 10 cents per barrel for a while.  That was a huge windfall for oil importing countries like Germany, Japan, and Italy.  It was a disaster for non-US oil exporters like Britain, Romania, the Soviet Union, and Venezuela.  The Venezuelan oil industry essentially evaporated for a while as most of its oil men came home to the US.

In the US, the oil glut made some fortunes, hurt the major oil companies, and put the US oil industry firmly on the side of protectionism, which was exactly what the world economy didn't need.  Protectionism divided the world into small, inefficient economic units crouching behind high tariffs, which caused economies to shrink further.  The oil companies weren't the only force for protectionism, but they did make it worse.

 An alternate wild card: In our history a borderline con man with a long shot came through.  Let's say that a different long shot comes through.  Some time between the stock market crash and the East Texas oil gusher, someone discovers gold in a remote area of the Amazon near the border between Brazil and Venezuela.  The gold was there to be discovered, though it wasn't actually discovered until the late 1970's, when it triggered a huge ongoing gold rush.

 Instead of an oil stampede in East Texas we end up with an Amazon Gold Rush as unemployed and desperate farmers and workers from the US and Europe flood into the Amazon in search of gold.  They quickly come in conflict with the local Indians and with tough Brazilian frontiersmen.  A lot of them die, or end up even more broke than they started out.  Enough of them get rich though that people keep flooding in.  

Many of the Europeans are German and Austrian Nazis.  Others are White Russian exiles.  A lot of people from rural parts of the American west flow in.  Parts of the Brazilian Amazon turn into a bizarre mix of the American old west and the European political movements of the 1930s, with Amazonian Indians fighting Nazis, White Russian exiles, Brazilians, and tough hunters and farmers from the US.  The East Texas oil fields remain undiscovered for the time being, as Columbus (Dad) Joiner retires his drilling rig and moves on to selling shares in Brazilian gold mines.

In Brazil the political and military impact is immediate.  Historically, Brazil got hit hard and early by the Great Depression.  In our history, the government of Washington Luis was swept away by a combination of popular and military uprisings and convoluted political maneuverings in October 1930 which installed Getulio Vargas.  The Luis government fell partly because of the general impact of the depression, partly due to long-term trends that decreased the influence of the traditional hierarchies that supported the Luis Government, and partly because it pursued a hard-money policy that eventually ran Brazil out of gold and hard currency.  In this time-line much of the newly found gold eludes official hands, but enough makes it to the Brazilian treasury to keep the Luis government in power in the short term.

The Brazilian government tries to keep control of the situation, but it simply doesn't have the capacity to project a lot of power into the area.  The gold-bearing areas are a long way from Brazil’s centers of population and military power.  Getting to the gold areas isn't easy, as prospectors quickly discover.  Getting gold out is even more difficult, as bandits, hostile Indians, and rival groups of prospectors try to intercept shipments.

One way or another enough gold gets out that it fuels an import and to a lesser extent a manufacturing boom in Brazil.  That helps the local economy.  It also helps the British economy, which has traditionally depended on South America for much of its exports.  Some of the gold makes its way back to Europe and the United States, boosting economies somewhat there too.

What impact does all this have?  Overall the Great Depression is not anywhere near as bad as it was historically.  The gold pumps some much-needed liquidity into the world economy.  More importantly it gives the more adventurous of the unemployed or newly destitute an outlet for their ambitions.  It also pushes bad economic news out of the headlines to some extent, which eases the psychological factors pushing the economy deeper into recession.  The depression still hits some countries hard, but some countries do much better than they did historically. 

For the British, this whole situation is a major plus.  Without competition from the East Texas oil fields, the British oil industry's fields in the Middle East and to a limit extent Africa and Venezuela are more valuable.  Also, they get the boost in export sales from newly rich prospectors in the Amazon, along with the people that exploit those prospectors.  Britain weathers the Great Depression considerably easier than it did historically.

The Germans, Italians, and Japanese don't fare so well.  Historically, the oil price collapse from the East Texas fields gave their economies a major shot in the arm.  Their balance of payment problems are far worse in this scenario than they were historically, and  while relatively robust economies elsewhere help their economies somewhat, all three countries are hit even harder than they were historically.

The fact that oil prices don't collapse gives the German synthetic oil industry a shot in the arm, but the relative weakness of the German economy makes it difficult for the Germans to invest large amounts of money on it.  Foreign exchange is a major problem for all three economies, limiting the amount they can spend on importing the raw materials necessary to build new industries like synthetic fuels or to build up their militaries.  If the Nazis come to power in Germany they will find it much more difficult to rebuild the German military than they did historically because they will inherit smaller reserves of gold and hard currency from the Weimer Republic than they did historically, and they will face higher oil prices in the early part of their reign.

Eastern Europe is a mixed bag.  Oil producers like Romania and to a limited extent Poland do better than they did historically.  The rest of the region is buoyed somewhat by the better economic conditions in the rest of the world, and with the exception of the Czechs their economies aren't industrialized enough to be affected too much by oil prices. 

The Soviet Union is both helped somewhat by the lack of an oil price collapse and hurt slightly by the additional gold on the market.  With higher world oil prices, Soviet industry is a little less prodigal with its oil.  Overall the Soviet economy is helped somewhat by the new situation and the Soviet military could grow somewhat faster in the early 1930s.  Some factors might off-set that somewhat though.  Marxist theory predicted a final crisis of capitalism, a depression followed by a major war.  If I recall correctly, Marxist economists felt that capitalism had avoided that crisis previously due to lucky injections of liquidity from various gold rushes.  They might see that pattern repeating itself and postponing what they considered inevitable.  The Soviets might not have gone so overboard on their heavy industrialization and military buildup without what they saw as an inevitable brewing war.  On the other hand the political dynamics of the Soviet state and its Great Power claims might have simply meant that ideology got tweaked a little to justify the hasty buildup.

The impact on the US is mixed.  The US does not become as dominate of a player in the world oil market as it did historically.  On the other hand, the major US oil companies are much more profitable in the early thirties than they were historically as the US doesn’t suffer the same deflationary pressures on oil in the early 1930s that it did historically.  The US economy benefits somewhat from the less severe world depression, and from the liquidity that the Brazilian gold pumps into the world economy.  I don’t know whether or not that would be enough to make the economy look sound enough to get Herbert Hoover reelected.  If Hoover got another four years things would start diverging very quickly.  A lot of the reforms that made a repeat of the stock market crash and banking collapses more difficult might not have happened, which would make another depression somewhat more likely.

I'm not sure what the long-range impact of this is.  Do the Nazis still come to power reasonably on time in Germany?  Does Roosevelt still get nominated and win the presidency from Herbert Hoover?  Does World War II still happen in approximately the same way it did in our time-line?  How would it play out if the East Texas monster fields that fueled so much of the Allied war effort still hadn't been found?  In a more favorable economic climate, would television take off much sooner but in a somewhat more primitive form than it did historically?  Television actually was around to a limited extent in the late 1930s, with around ten thousand sets sold before the industry was shut down for the duration of World War II.  What about rocketry?  Nuclear power?

More importantly, how good of a story setting would this version of Brazil make?  Nazi's, Russian exiles, international intrigue, poison arrow Indians, a gold rush, and outlaws in a Wild West atmosphere.  Add in exotic animals and maybe even an element of cryptozoology if the rest of it doesn't keep me too busy.  Sounds like a fun place to write about from the comfort of my living room.

But what about? 
Would this really have much of an impact on the Great Depression?  I doubt that this little switch would eliminate the Great Depression and I'm not entirely sure it would make much difference at all.  The timing of the gold rush and the way the media played it would probably be crucial.  Economies depend to a very large extent on mass psychology and that is very hard to predict.

Would the Brazilian government of 1930 really allow a Wild West environment to develop in the Amazon?  I'm researching that, but I'm not really sure one way or the other.  Based on very limited research I’m not very impressed with the vigor or foresight of the Luis government.  If Vargas took over at some point, that part of the equation might well change considerably.

Would the technology of 1930 allow the extraction of the Amazonian gold?  That’s another thing I’m checking.  It’s one thing to find gold.  Sometimes economically extracting it is a much more difficult thing.

Would a gold rush really develop given the difficulty in getting to the site of the gold?  I don't know.  There would certainly be a great deal of incentive for miners to get there, but I'm not sure a lot of miners physically could get to the sites involved.