While there have been significant immigrations to Scotland [the Irish (twice), the Flemish, the Normans, Britons, English and the many countries of the Commonwealth], Scotland is overwhelmingly a nation of emigrants and has been for centuries. Many Scots enlisted in foreign armies, especially in the 17th century; others became Baltic Traders; others still wandered south to England. Scots even tried their hand at colonization at a place called Darien on the Isthmus of Panama in the 1690s. Darien, unfortunately, was a total disaster and almost bankrupted the country. As the Thirteen American colonies belonged to England, the Scots, technically, were not allowed to settle there. Emigration really picked up after the Union of 1707, when the American colonies became British and the Scottish economy began to change dramatically. In the 19th century Scotland was just behind Ireland and Norway in percentage of population lost to emigration.
Studying emigration in the sending nation really gave me some interesting insights. As Americans our national narrative usually sees immigration as a positive thing. Energetic and enterprising people up and left their oppressive homelands for religious freedom and economic opportunity. (Of course the other side of this narrative is "keep 'em out, we don't want 'em"; nativism is not new). However, in the sending countries the narrative is quite different. In Scotland where I lived (and in Sweden, Norway and the Netherlands which I read about) emigration is seen as a national tragedy. Elites and government are seen to be at fault - they colluded in some way to force these people out, either by raising rents or encouraging industrialization. Within some emigration stories is the idea that the those with prospects and wealth left, leaving the 'losers' at home. Now, who wants to be a country of loser, left overs?
What I learned though, during my dissertation research, is that while there were all sorts of problems within Scotland that led to the departure of thousands who might have otherwise stayed, migration is a constant of human society. It is neither good, nor bad, but simply is. When resources are scare and the people are plentiful there must either be an increase in the resources or a decrease in the people. For millennia, when agricultural technology was limited, it was the number of people who were decreased through migration.
For a short introduction to Scottish Emigration (900 years in 30 pages) see, David Armitage, "The Scottish Diaspora," pp. 272-303 in Scotland: A History edited by Jenny Wormald. This book is a collection of essays which cover Scottish history from 1100 to the present. I paid full price, it's now a steal. The shipping would probably cost more than the book! Or, just try your local library.