On October 29, 1929 . . . 
The New York stock market crashed. Over the next 3 years the Dow Jones Industrial Average dropped by 85%. Thousands of investors were wiped out.

Banks failed by the hundreds, victims of the boom in installment buying that helped feed the economy in the 1920’s. There was no deposit insurance, and so a bank failure could result in depositers losing their life savings. Thousands of businesses also failed and as a result 30 million people worldwide were thrown out of work—unemployment reached 30% in the United States and Canada with almost nothing in the form of government aid to cushion the blow.

In Canada . . .
one woman appealed to R.B. Bennett, the Canadian Prime Minister at the time,  for help in finding work because:

. . .  I am faced with starvation . . . I have applied for every position that I heard about, but there were always so many girls who applied that it was impossible to get work . At first I ate three very light meals a day; then two and then one. During the past two weeks I have eaten only toast and drunk a cup of tea every other day. Day after day I pass a delicatessen and the food in the window looks oh so good! . . . and I’m so hungry! . . The stamp which carried this letter to you will represent the last three cents I have in the world . . .

The Canadian gross national product declined from $6.1 billion in 1929 to $3.5 billion in 1933.

Government Action Was Often Ineffective 

The crash is usually taken as the beginning of the Great Depression but the actual causes were deeper and more complex—and they reached further back in time. Many of the major economies in the world were in trouble in the 1920s: England was suffering from a loss of markets in her empire; Austria was a basket case after  the first world war; Germany had gone through a massive inflation that wiped out the value of the Mark and was paying ruinous war reparations; the Soviet Union had its access to world markets blocked following the bolshevik revolution and the civil war that followed. Huge crop surplusses in cereal grains in the mid 1920s caused grain prices to plummet initiating an agricultural depression in the United States and Canada. The United States was now, economically, the most powerful country in the world with Europe heavily indebted to it, but instead of taking a leadership role to stimulate the world economy, its actions made things worse. Congress enacted high protective tariffs causing a chain reaction: world trade dried up driving unemployment still higher and the world deeper into Depression.

In Canada Prarie Incomes Plummeted, . . .
a result of the wheat crash in 1928, followed by the worst drought in prairie history. Saskatchewan, the hardest hit, saw its farm income fall by 90% in two years. 66% of the province was on relief. The minum annual income required to meet the most  basic of requirements for food, clothing and shelter was $1500 per year but only 30% of Canadian families had an income of even $1000/year.

The Trek to Ottawa
The Bennett government started relief measures for the thousands of men who were travelling back and forth across the country looking for work. Some were sent to work on farms for $5 a month. One of the measures—the work camps—became a flashpoint. Unemployed and starving workers were organized into work camps supervised by the military where they were paid 20¢ a day ($50 a year!) for 6 ½ day weeks. Living conditions were terrible. They lived in unheated quarters in remote and isolated areas. The workers soon organized themselves with the help of the labour movement and made demands for better conditions, social insurance programs, the right to congregate and solidarity with the labour movement. The government refused their demands and banned the movement.

What followed was to became one of the most famous labour events of the depression. The strike leaders decided to trek to Ottawa to meet directly with R.B Bennett and put forth their demands. 1,500 men set out from BC and The On to Ottawa Trek was avidly followed by the press. But it ended in Regina with what has been called a police riot. Police attacked a group of 3,000 supporters of the trekkers leaving one man dead, hundreds injured and downtown Regina with severe property damage. 

The trekkers were radicalized by their experience. Three years later when the call went out for vounteers for Spain, more than 400 of them would answer.