There was the Venezuelan Crisis on 1895 between Great Britain and the USA over the Venezuelan border. Continuing along the theme of GB/USA crises, there was a number of them during the 1830s and 1840s, mostly to do with British North America. The main ones were the Rebellions of 1837/1838 in the Canadas and the American Patriot/Hunters Lodges support of the rebels, the Aroostook War of 1839 and the McLeod Trial of 1841 and the Creole Affair of 1841. The American government and people were strongly anti-British during this period and it was easy to elevate an incident to crisis proportions. Fortunately, common sense prevailed and the Third Anglo-American War was prevented.
Have a look at The Crisis of 1830-1842 in Canadian-American Relations (Albert B. Corey. New York: Russell & Russell, 1941 and 1970). It will give you a good introduction.
And don't forget the Trent Affair of 1861!
All the best,
Nil Sine Labore
OMRS 4556, MCCofC 782