I would like to tell you about a country called the Grand Union of America, or GUA. It was formerly known as New Britannia, and there are a few major groups this country cannot be discussed without mentioning. First are the Pilgrims. Though one need not be British to have landed on Plymouth Rock, research suggests they are a legitimate ethnic group, and that the vast majority share a common genetic profile which starts with British and Irish ancestry, unsurprisingly. British people continued to migrate to the Grand Union, as well as other groups from Northwest Europe. Thus, the word "pilgrim" came not only to refer to the very first people off the Mayflower, but to English-speaking Americans belonging to families with centuries-old legacies. Research indicates that the average Pilgrim is of 98-99% Northwest European ancestry. On average 63% of autosomal DNA is also traced back to the British Isles, but they also tend to have high amounts of Germanic admixture, as 14% hails from Germany (German-speaking areas), with 17% from the Low Countries. 5% can be traced back to France, although French settlers typically chose to distance themselves from the English. This brings me to my next point.
Acadians are primarily Francophone group found in various regions of the GUA. As can be inferred, they make up a smaller group than Pilgrims. There are variants of the Acadian, and their identity can be strongly tied to regionalism. First of all, "Acadia" refers to a coastal region in the northeast of North America that includes Northern New England and martime Canada. This is where it all began, their Plymouth Rock. Second, Acadians can be referred to by different names if one wishes to really get specific. In the former Louisiana Territory, you will find "Cajuns." In Quebec, you will find Quebecois. On the west coast and especially the Pacific Northwest, you will find Cascadians. The Acadian population is estimated at 57-66 million strong.
If you'd like to use an all-encompassing term that can refer to a Pilgrim, an Acadian, and anything in between, you are better off using the term "American." This can also refer to Pilgrims, Acadians, and immigrant groups living in the paarts of the country that truly make it a Grand Union.
In a world where the concerns and interests of the Thirteen Colonies were given considerable weight in British political discourse, New Britannia stood as a shining example of successful colonial governance. Its capital is Philadelphia. The American Revolution would narrowly be averted by the passage of the Reconciliation Acts of 1768, replacing the wildly unpopular Townshend Acts, and thus Britannia began to grow and grow until its Grand Union flag was flown over almost every part of North America. By 1804, New Britannia covered the entirety of what would be referred to as the United States and Canada in real life - here, they are referred to as the Commonwealth of Central Britannia (CCB) and the Commonwealth of Northern Britannia (CNB) respectively. Commonwealths function as autonomous parts of the republic.  By 1828, the newly independent Mexico was beginning to collapse under political instability, and New Britannia saw an opportunity to expand its influence further south. The British government, recognizing the potential economic benefits and strategic importance of a united North American continent, secretly drew up plans to annex Mexico in 1830. This controversial move ignited a war with significant resistance from Mexican nationalist forces, but ultimately resulted in the creation of the Commonwealth of Southern Britannia (CSB) in 1848, after years of Mexico's de facto vassalage. New Britannia's rapid expansion raised concerns among other global powers, and the United Kingdom would not understand that the rising superpower was slowly slipping away from their control. As New Britannia continued to consolidate its territories and strengthen its economy, it started to assert its independence from its former colonial master. This lead to the Great War - fought from 1875-1889. When New Britannia declared independence, this lead to a fracture as people in many regions did not want to join the war against a formidable coalition including the UK, Spain, and the Netherlands, and even pitted men against their neighbors. Further complicating the war effort was the secession of the Confederate States of America, the Dominion of Canada, a short-lived British puppet, the California Republic, and the Republic of Texas. During this time Chicago served as the de facto capital. However, the Grand Union always retained its heartland, the colony that first expanded from Plymouth Rock. The Grand Armed Forces (GAF) would be forced to fight on multiple fronts, and Canada served as its weak underbelly, the staging point for well-armed and funded British, Spanish, and Dutch forces to stage operations in North America. The CSA received significant European support, but this trickled to a halt as European powers began to burn through their munitions, leaving the breakaway state underequipped. In addition, Americans here (again, this is a shared identity) resented the foreign armies and viewed them as invaders. By 1880, the situation became untenable. Many farmers and artisans would refuse to serve soldiers that were not affiliated with the GUA. 
Work in progress.