Grand Duchy of Aleska - Aleska's blue color and the use of fleurs-de-lis comes from the country's origin as a French settler and trading colony; the Grand Ducal House of Aleska is also a patrilinear Capetian cadet branch. The star in the upper right is Polaris, the North Star, while the fleurs-de-lis are arranged to form the shape of Ursa Minor attached to Polaris.
Republic of Ayiti - In modern times, the flag is said to be a reference to the sea, the dry land and the dark night in which the War of Liberation was planned and fought; however, the flag has its origin in the plain black flags which were raised in the Ayitian Revolution, and then flown as jacks (with the legend in large letters -- LIBÉRATION -- in white) with a variety of other symbols and color bars as Ayiti began its long, and ultimately successful (with foreign support), naval war of attrition against France. Gold and blue bars (though flown at the top of the ensign) were the particular ensign used by Jean-Baptiste de Libertad, one of Ayiti's most successful naval commanders, who even dared to attack French shipping in sight of Brittany -- and got away with it. He was eventually elected king, and later generations adopted his particular color scheme when they decided to be rid of the purely black banner, which had the problem of being mistaken for a flag of piracy.
Grand Duchy of Canada - Canada uses a flag quite similar in form to the very old Capetian symbol of their forebears in France, but the fleurs-de-lis have been replaced with maple leaves, a prevailing symbol of Canada whose first adoption technically postdates the point of departure OTL, but by a matter of only a few decades.
Republic of Cansas - Cansas' flag represents the two great, important rivers in Cansas, the Missouri and the Arcansas, with the two rivers surrounding fertile cornfields represented in gold.
Commonwealth of Carolina - The Carolinian flag originates in an early flag of revolt which was simply blue; four white stripes were added to more easily distinguish the Carolinian flag from the Blue ensign at sea during the War of Anglo-American Independence, and this was ultimately adopted as the national flag following independence. In the early twentieth century, a cross was added as a symbol of Christian faith and brotherhood in Carolina, though its addition was intended to emphasize Carolina's understanding of the "Natural Christian Order" and reject efforts toward property and equal civil rights for Black Carolinians. The cross remains as the Carolinian state still denies both.
Kingdom of Cuba - the flag of the Kingdom of Cuba is inherited from the battle-flag of the Spanish Empire, which is itself a modification of medieval Burgundian battle-flags. Cuba is considered the true and primary successor state of the Spanish Empire in the Americas, as it is ruled by the Habsburgs, while even Spain itself is not.
Kingdom of Florida - the Kingdom of Florida is ruled in personal union with and is a dependency to Cuba, and its flag reflects this; it is modeled on Anglo flags derived from the Red, Blue and White ensigns of the historical English Empire, but using the colors and symbolism of the Spanish Empire.
Grand Duchy of Grand Aquitaine - Grand Aquitaine is, of course, named for Aquitaine in France; its flag is modeled on the Coat of Arms of the City of Bordeaux in France, with a few elements changed, modified and mirrored.
Republic of Louisiana - The colors of the Louisianan flag represent the Three Races in Unity -- (American) Indian, White and Black, of which it is said that Louisiana's culture, tradition and people are an essential and indivisible union. The letters "SPQL" which appear on the flag are modeled, of course, on SPQR, a traditional sigil of the Roman Republic, on which Louisiana has historically modeled itself. Diplomatic legations to Louisiana continue to be posted as emissaries to "the Senate and People of Louisiana" despite the abolition of the Senate in constitutional reforms more than half a century ago (an identical situation to neighboring New Spain), and "the Senate and People of Louisiana" is still considered a legal alternative official name for the Republic.
State of Maryland - It's essentially identical in origin to the OTL flag of Maryland, except that IOTL, the Calverts retained possession of Maryland until independence; ITTL, the main line of the Earls of Baltimore died out and Maryland passed into the hands of the Earls of Marlborough before independence -- in whose hands it remains to this day, though the style "Earl of Marlborough" is now used as a courtesy title for the heir-apparent, as Princess (or, when there is a male monarch, Prince) of Maryland supersedes it.
Grand Duchy of Michigane - the symbol on the flag is said to be the sun rising over Lac des Hurons to shine over Michigane, while in the lake are three golden fleurs-de-lis to represent the House of Michigane, which is a patrilinear Capetian cadet branch.
Kingdom of New England - New England's flag is based on the White Ensign of England, which has been defaced with two pine trees - which represent the Dutch and the English settlers of New England (as New York has been incorporated into the Kingdom of New England) - and blue star in the upper right represents New England's very old whaling tradition, with Polaris shining at night to guide the men of New England back home. New England retains St. George's Cross both because it is New England, making the use of England's flag fitting in itself, but also as New England remains in personal union with England.
Kingdom of the Haudenosaunee - Purple is a color which has longstanding historic and traditional value to the Iroquois, both ITTL and IOTL; the flag of Haudenosaunee has a five-pointed star, which represents the five core Nations of the Haudenosaunee. The symbol we think of as fundamentally Iroquois IOTL, the flag based on the Wampum Belt, exists in TTL symbolism of the Kingdom - as it very long predates the Point of Departure - but it is represented in their coat of arms rather than in the flag.
State of New Jersey - New Jersey's flag is based on the Blue Ensign of England, but St. George's Cross has been replaced with a red St. Andrew's cross, the symbol of the Bailiwick of Jersey for which the state is named. The "Ensign" is defaced with a horse rampant, representing both New Jersey's reputation before its independence of breeding the best horses in the Colonies, and for the decisive role that New Jersey's first prince played leading New Jersey's cavalry formations in the War of Anglo-American Independence, particularly at the final, decisive Battle of Delaware Falls.
United Republic of New Spain - The flag of New Spain is modeled chiefly on ancient Roman imperial standards, though the eagle which would have been mounted atop the poles bearing the earliest version of the flag has since migrated onto the flag itself. Gold and Red are both longstanding colors in Aztec and Spanish symbolism and so were naturally inherited by New Spain, particularly as the colors also invoke the Virgen de Guadalupe, an important part of New Spanish religious tradition from long before the point of departure. The eagle is mounted in Roman style, but it is a native eagle, devouring a snake while sitting on a cactus, a pre-Spanish symbol of the royal city of Tenochtitlan and its successor, Mexico City, both ITTL and IOTL -- which, both ITTL and IOTL, became a national symbol of an independent state with its capital there. The blue bars on either side especially invoke the protection of the Virgin, the blue being a more traditional European color of the Virgin and twelve golden stars representing the Crown of Stars in the Book of Revelation. ITTL, this combination reflects that early New Spanish armies, both during the War of Independence and afterward, would fly both a gold and red banner with various symbols or words on it, mounted by a silver or golden Mexican eagle devouring a snake while sitting on a cactus, while a separate banner of the Virgin would be carried alongside it.
Commonwealth of the Ohio - A Blue English ensign, but this one has what OTL calls the Union Flag. ITTL, the Union Flag has gone in and out of fashion as a symbol of Great Britain, and at the time of Ohio's adoption of this flag, it was out of favor back in Europe but well-known enough in America that it could be considered a neutral symbol of Anglo-Scottish heritage without invoking the English or Scottish Crown, part of what drove the combined Union Flag into complete disuse in the 20th century. It is defaced with a compass, which pays tribute to the explorers and early settlers of the Ohio Valley.
Commonwealth of Oregon - An English Red Ensign but, mimicking Ohio (whose independence long predates Oregon's), it uses the Union Flag as a symbol of Anglo-Scottish heritage. The symbol defacing it, on the bottom of the flag, represents a fasces, symbolizing republican authority as well as national unity -- initially, it was intended as a slight against the State of South Oregon which gained independence separately, and which many Oregonians saw as within Oregon's natural borders, though today Oregonians and South Oregonians alike downplay this element.
Commonwealth of Pennsylvania - Pennsylvania's flag reflects its origin as a colony founded for the sole purpose of tolerating dissenting religious traditions. It invokes common human heritage and peace by using the symbol of a golden dove on a white banner, bearing an olive branch, which is a depiction of the dove which indicated to Noah that the Flood was beginning to recede; it invokes both the color white, the dove and the olive branch as symbols of peace, as well as calling attention to humanity's common ancestor to promote similarity over difference.
Grand Duchy of Sioux - Despite its name, Sioux is very much a country with tension between its native, white, métis and Black populations; the cross flag is a defiant statement of the Christian faith of the Siouxan state in contrast to the traditional spiritual practices of the Lakota native people. It similarity to the Nordic flags ITTL is debated, and it is almost certain that the Grand Duke who adopted it knew it was similar to the Nordic flags, but it has no specific Nordic connotation; the colors are simply reversed from France's war flag.
State of South Oregon - The blue color of South Oregon's flag invokes the English blue ensign, and, historically, it bore the English flag in the canton, but it was removed when the current version of the flag was adopted. The four diamonds represent South Oregon's "Four Diamonds", the four chief resources that sustain South Oregon -- silver, wood, gold and copper.
Kingdom of Virginia - Green was the color of the uniforms used by Virginian soldiers, first in the War of Anglo-American independence and then afterward, and became seen as the royal color after the establishment of the kingdom, in like way to orange in England. The pyramid invokes ancient Egypt, seen as a source of ancient power and legitimacy by classically educated Virginians in its early days, but also the pyramids of New Spain, which was a major part of Virginia's acquisition of independence -- though modern Virginians downplay this and emphasize the Egyptian aspect. The pyramid also represents the social structure of Virginia, with many layers, a large lower class leading up to a narrower top. The top of the pyramid is cut off and colored golden, showing that G-d is apart from and above whatever social structures exist for man, and is not subject to any earthly royal authority. The All-Seeing Eye inside a triangle, representing the Trinity, further emphasizes the detached portion's association with G-d. Many modern Virginians object to this symbol because it was founded on and based upon the racial caste system and, of course, slavery. which were still institutions in Virginia at independence. The flag has the words "Deo favente", a Latin motto meaning "With G-d's Favor", which was used as a motto in the American colonies before the Point of Departure and is the origin of the U.S. lesser motto "Annuit coeptis" ("He Has Approved What We Have Begun") IOTL, which was chosen IOTL instead of Deo favente because it had thirteen letters.