I believe a number of the American loyalists immigrated to the Nova Scotia region... perhaps this could be represented by an event following American independence... say depopulating the American coastal provinces slightly, and boosting Nova Scotia, Acadie and Micmac (but ONLY if they are English-owned). This could also be a tweek of your 'persecute the loyalists'... instead of the random boosts, it would check those provinces first.
Also... I know it historically happened after the timeframe of the game, but the formation of the Republic of Texas could be an interesting source of some events. (Historically, it was a Mexican territory following their independence from Spain, but was very loosely governed and quickly became independent in a small war, as most of the region's residents were immigrants from the United States, esp. Kentucky and Tennessee. It was then annexed by the United States about a dozen years later, and that helped start the Mexican-American war of 1846-48.)
Also... I know it historically happened after the timeframe of the game, but the formation of the Republic of Texas could be an interesting source of some events. (Historically, it was a Mexican territory following their independence from Spain, but was very loosely governed and quickly became independent in a small war, as most of the region's residents were immigrants from the United States, esp. Kentucky and Tennessee. It was then annexed by the United States about a dozen years later, and that helped start the Mexican-American war of 1846-48.)