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. There are an estimated 330 million Pilgrims. This brings me to my next point.
Acadians are a large, 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 101 million strong. There are Italian, Spanish, and Portuguese Acadians as well as the French.
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." 
As far as basic information goes, its capital is Philadelphia. This is part of the state of Galloway (named after Joseph Galloway, a major figure in the passage of the Reconciliation Acts of 1768). Galloway obviously includes Pennsylvania but also includes some of the other core colonies, some of the oldest such as Virginia, Maryland, Delaware, New Jersey, and New York. Other foundational states include New England (MA, CT, RI, VT, NH, ME), the Canadian Maritimes, Ontario, Quebec, and Carolina (NC and SC.). Each state is important, but key newer ones include Florida (Florida and Cuba) Austin (Texas, OK, KS, WY, UT, AZ), Dixie (TN, AK, LA, MS, AL, GA), Huron (MI, WI, MN, IA, IL, IN, OH,MS, KY.), Serena (CA, NV, OR, WA), and Montalucio (ID, MT, CO, ND, SD, NE.) Central Britannia, which is pretty much the core of the entire cross-continental country, is predominantly European, and they account for 81% of the population, although Hispanics, Africans, and Filipinos also live in there. However because of past trends many of these groups do have significant European admixture and some with very high admixture can look indistinguishable from Europeans. In this timeline, slavery was abolished in 1814, so it has fewer Africans, as they account for 2.5% of the population of the CCB. Additionally, half repatriated to Liberia (Note: In this scenario, Liberia has thrived, and with American guidance and investment it became comparable to South Africa.) The national currency of is the Grand Union Dollar ($).
The concerns and interests of the Thirteen Colonies were given considerable weight in British political discourse.  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, Canadians 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. These were called the Grangers. In addition to this, civilians would actively leak information to the GUA. Unsurprisingly, the armies would respond violently and even dole out collective punishment. Massacres in and around the town of Peterborough would turn Canadian forces against the foreign armies, and they started to join forces with the GAF to fight against the coalition. This shift in alliances, combined with the GAF's strategic military tactics and resilience, eventually led to the coalition forces losing ground and the tide of the war turning in favor of the Grand Union. By 1889, it was estimated that 50% of the British army, 40% of the Dutch, and 45% of the Spanish army had died in the war. Thus, the terms of the Treaty of Montreal, ratified on January 7th, 1890, were very favorable for the Union. Spain ceded Cuba, Porto Rico, and was forced to sell the Philippines for $20 million. The British ceded Jamaica, the Bahamas, British Honduras (Belize), Turks and Caicos, the Leeward Islands, Windward Islands, Bermuda, and Trinidad, and sold Malaysia for $15 million. The Netherlands ceded the Dutch East Indies, that is, Indonesia. Additionally, the Grand Union left a complicated legacy in some of its overseas territories, such as Mexico, Cuba, Malaysia, and the Philippines. Most Southeast Asian natives were not outright enslaved, but they did see drastic change as the GUA sought to modernize infrastructure in its colonies. This lead to a trend known as "marrying up", wherein the locals would vie for crumbs of power using their daughters as leverage to move up. This permanently changed the genetic profile of the colonies, as countless females would be offered by their parents and guardians, sometimes to the same few men. Male children were seen as a liability. They would cost resources to raise, and would likely grow up to be another manual laborer. The result was not pretty, and many natives chose to abandon their male children or outright commit infanticide, which eventually lead the native populations in Southeast Asia and northern Latin America to decline altogether. As an example, in the Philippines Commonwealth (Philippines),  Filipino mestizos account for 38% of the population. Europeans account for 27%, and Pinoys 24%. The remaining 11% are mostly Asian, although not Filipino. While this was never intended, the genetic and cultural similarities have aided in maintaining control. In 1904, the Grand Union annexed Panama, and by 1906 it would control all of Central America as the Commonwealth of Panama. Haiti and the Dominican Republic were some of the only countries to maintain sovereignty in North America. Throughout the 20th century, Indonesia, the Philippines, and Malaysia were nominally granted independence, but they are still seen by some as puppets, and they continue to be members of the Grand Union-lead Treaty of Reciprocal Assistance (TORA), alongside countries including Argentina, Portugal, France, Norway, Italy, and Denmark. It's a binding alliance. It was first inked in 1936, and seeks to counter the influence of the German Empire.

The people in this nation enjoy watching sport. The most popular are rugby union, baseball, and American football. Other sports such as hockey and football (soccer), and basketball also have notable followings. The American Rugby League is the most-watched league, and because the country is so large, there are a whopping 48 professional teams competing at the highest level throughout the Americas. This varies with relegation and expansion. Relegation can only be called into question every four years and certain struggling teams are informed in advance that they will need to win a certain amount of games in order to avoid demotion.The ARL also has a draft, and minor leagues. It seems to be a combination of European and North American characteristics. Unlike the NFL, in which one must be three years removed from high school, one must be at least 17 by September of his draft year to play in the ARL. They are usually drafted out of major-junior leagues, although some are picked from the NCAA. Thus, college rugby is not as relevant as college football. Females play volleyball, but is usually played until the college level. Other leagues such as the MLB and NFL also have more teams. Southeast Asia does not participate in North American leagues. For example, there are MLB and ARL teams in Cuba, Mexico, and Guatemala. The rivalry between the Grand Union and the UK runs deep, and this extends into sports. Many Americans see the Grand Union as the successor to the British Empire.

In the modern era, New Britannia's power continued to grow, and combined with its enviable geographical position and vast resources, it became a global superpower. With a mainland featuring most of North America, it's the world's largest country by land area, and the Americans are quite proud of this. The total population is estimated at around 490 million in the modern era, with 318m in the CCB, 47 million in the CNB, 105 million in the CSB, 7 million in Panama, and 13 million in other areas. This ranks second after China. Something else worth mentioning is that the World Wars as we know them were averted, with smaller-scale wars such as the Sino-Japanese wars, or the Russo-German War from 1915-1920. Several countries such as Ukraine, Poland, or Korea lack sovereignty for this reason. It's still an age of empires.