A number of factors forced or encouraged people to leave Scotland after 1830. The Highland Clearances and competition for land, jobs and housing caused thousands of Scots to travel to the New World.
Land was plentiful. In the American West and Canada, land was offered on a loan basis. This attracted experienced farmers and labourers.
In Australia and New Zealand, cattle and sheep farming was a prosperous industry, so this possibility to make your fotune attracted many.
Gold rushes
Discovery of gold led to gold rushes:
Discovered in California in 1849.
Discovered in Australia in 1850.
Discovered in South Africa in 1855.
Gold rush begins in New Zealand in 1861.
Employment
New settlements needed new infrastructure, road networks, new administration centres, schools and churches - this created much employment. Wages were higher in the New World and living conditions were much improved.