While Cinco de Mayo is rather popular and well-celebrated in the US, it has only limited recognition within its own country of origin, Mexico. Most Americans only know that it's about some sort of battlenote It commemorates the Battle of Puebla in 1862, when the French invasion of Mexico was temporarily stalled by a much smaller Mexican force.You can read more here., and most assume that it's the actual Mexican Independence Day, which it isn't (that would be September 16th).
Cinco de Mayo was promoted by Chicano activists in the 1960s as a celebration of their heritage, much like St Patrick's Day below. The holiday was chosen due to Mexican-Americans identifying with the indigenous Mexicans triumphing over European invaders, and has since grown over the years into the parades and cultural events we have now (as well as, yes, endless margarita specials). Within Mexico, it's really only a big deal in the state of Puebla, where the battle occurred; although some other areas celebrate as well, it's not even a federal holiday there. It's more of a Mexican-American than a Mexican holiday.
St. Patrick's Day in Ireland is a boisterous but religious holiday: historically, it was celebrated by spending all day in church, and then drinking heavily later. Irish-Americans, however, turned it into a celebration of their unique immigrant culture. The first St Patrick's Day parade was in New York City in 1762, while the first in Ireland was in Dublin in 1931. Over the years it's become, like Cinco de Mayo, an excuse to throw a theme party and drink a lot. In England, St. Patrick's Day is also far more widely celebrated in England than St. George's Day, though mostly as an excuse for drinking. This can be largely attributed to the Guinness Corporation.
Halloween is more popular in the US, despite its Irish origins as Oíche Shamhna (Samhain), the ancient New Year's Day; the bridging of the boundary between years is mirrored by the weakening of the gap between the world of the living and that of the dead. Bonfire is a calque of the Irish tine cnámh, "bone fire". Americans turned it into a secular holiday about playful scares, costumes and candy. The new holiday has spread throughout countries such as Germany, Austria, and even back into Ireland, where the new style has largely replaced the old.
It's a double example in that the holiday is one of the many pagan holidays Hijacked by Jesus to help converts adjust to the new religion. All Hallow's Eve is the evening before All Saint's Day, was a minor prelude to the much larger celebration the next day, and was actually completely forgotten among Christians for years before some Americans decided to revive it and the modern version was born. Despite popular belief, it was not the pagans who wanted to honor the dead. The pagan holiday that Halloween replaced, Samhain, was merely a harvest festival; the Church is what installed devotion to the dead (and it was meant to serve as a reminder to pray for the souls in Purgatory, not honor death itself.)
El Dia de los Muertos ("The Day of the Dead"), a uniquely Mexican holiday (November 2nd), is seen by many in the United States as "the Mexican Halloween" (and, indeed, is roughly equivalent to All Souls' Day, an already-existing holiday in English-speaking Catholic countries and regions), and is beloved in the U.S. for precisely that reason. Of course, it helps that all those painted, flowered skulls are "exotic" and "creepy" and "cool" to so many North Americans, and also that the "Goth" subculture has appropriated the holiday's trappings. Oingo Boingo, the punk/new wave band founded by Danny Elfman that gained great popularity in the 1980s, has also done much to promote the Muertos imagery to fans around the world.
Don't forget Guy Fawkes Day. Had November 5th only been about a failed plot to blow up Parliament, it would only be a forgotten historical footnote. Yet 400 years later, we in England still burn effigies on a very big bonfire. Not coincidentally, only a few days after Halloween. Go figure.
International Worker's Day, or "May Day," is observed in many countries around the world (it also overlaps with the religious May Day and Walpurgisnacht, celebrated at the same time), and commemorates the Haymarket riot/massacre in Chicago in early May 1886 (it was part of a convention that first endorsed the eight-hour workday). However, the US doesn't celebrate its Labor Day on 1 May, on account of distrust of socialism in the US in general and the painful memories of Haymarket in particular - Labor Day in the US is whatever is the first Monday in September.
Chanukah (also spelled "Hanukkah") is proportionately more popular among Jews in the West (specifically America) than in Israel or elsewhere. Being the least important and most recently ordained holiday on the Jewish calendar, in Israel (where most of the population is Jewish and a significant number are Orthodox), it tends to be overshadowed by more serious holidays like Passover and Sukkot. American Jews, however, elevated the importance of Chanukah to compare with Christmas, so that they too could enjoy a "Holiday Season" with their Gentile neighbors. Jewish parents added the custom of gift-giving so their children would not feel left out (although there was an old tradition of giving money, or gelt, at Chanukah among Ashkenazi Jews, it apparently just isn't the same).
In modern Israel, Chanukah has gained some importance... as a nationalistic holiday celebrating Jewish military prowess, which is what the holiday originally meant.
In what could be called a possible example of We All Live in America, the original An American Tail shows the Mousekewitz family (a family of Jewish mice) celebrating Hanukkah...even though (for the moment, at least), they are Russian peasants living sometime around the turn of the twentieth century. At least the Mousekewitz's celebration of the holiday is a very small-scale affair, being based exclusively in the home and with only the immediate family in attendance.
This happened with Christmas in Japan, in spite of the fact that Christians make up less than one percent of Japan's population. Not surprisingly, the holiday in Japan is extremely secular and is treated as a romantic holiday. Of of the most unique aspect is the eating of Christmas cake, a white whipped cream cake with strawberries. It is also used in a common expression about the marriageable age of women. And then there's the Christmas KFC bucket of chicken, which means KFCs are serious business during the Christmas season (with restaurants taking Christmas order reservations months in advance) because the Japanese wanted to try that Christmas turkey dinner they see on American TV shows. The average Japanese household makes this impractical so fried chicken is the best substitute they can come up with.
This can even occur within a single country. Columbus Day, which celebrates a Genoan's "discovery" of America, is infinitely more popular in New England and northern states. It is basically forgotten and unremarkable in other areas of the U.S., where Native American groups, due to the justified grievances that they have with Columbus, have been very successful in limiting its recognition. Unless you're trying to mail something, of course.
It might also have to do with respective populations of Italian immigrants and their descendants, which are higher in the northeast. A century or so ago, when it was difficult for Italians to assimilate in the U.S., they sometimes latched on to Columbus as a connection between ethnic pride and American patriotism ("Why are you calling me Italian like it's a bad thing? An Italian discovered your country!") and made it a bigger deal than it already was. It should be noted that Columbus, though (geographically) an Italian by birth, identified as a Spaniard for most of his life; his descendants are likewise assimilated Spaniards who just happen to have Italian ancestry.
An argument between Italian Americans (used to using Columbus Day for a sort of Italian Pride parade) and Native Americans is the centerpiece of an episode of The Sopranos (Season 4, Episode 3, "Christopher"). Silvio Dante in particular gets pretty riled up, to everyone's annoyance, even though they agree with him.
Likewise, Mardi Gras is only a big celebration in South Louisiana and Mobile, Alabama, while in Europe it is a more common holiday. This is due to the fact that most American Christians are Protestants and Mardi Gras is supposed to commemorate Fat Tuesday, the very last day before Lent. Unlike some forms of Protestantism (e.g. Lutheranism and High Church Anglicanism), American Protestantism, which tended to be either Calvinist/Reformed, Baptist, or Low Church Anglican, historically downplayed Lent or even derided it as a "Popish" (i.e. Catholic, but meant as an insult) superstition, so the last day before Lent was just another Tuesday.
It should be added that in Australia, although mainly the in Sydney, Mardi Gras is treated as a gay pride holiday, and attracts about 70,000 people each year and earns the city 30 million dollars in tourism income.
And Mardi Gras is celebrated as per the way Louisianians celebrate it throughout the South, especially in states that border Louisiana. Outside of that region, a similar celebration called Shrove (or Pancake) Tuesday is celebrated in areas with a great English/British influence such as Canada (or Britain itself). In those areas, it's commonplace to make one's main meal a big plate of English-style pancakes, which are thin crepes with sugar and lemon juice sprinkled on top. (Or one might eat Scottish-style pancakes, which are the fluffy kind Americans are famiiiar with.)
Even the Fourth of July is not immune to this trope. After the American Civil War, the people of Vicksburg, Mississippi did not celebrate the holiday until it was made a federal holiday in 1931, as that day marked the surrender of the town to Union forces.
Casimir Pulaski Day (first Monday in March) is another probably less well known version of this trope — less well known because it's only observed by Illinois, and to a lesser extent Wisconsin and Indiana. It seems a little strange at first for a state to have a full holiday (schools, libraries, and government offices closed) for a guy who never even set foot there. Outside of this area, the only people who are likely to know of the holiday are fans of Sufjan Stevens. May be because Chicago has more ethnically Polish residents than Warsaw, and Wisconsin is the most Polish state in America per capita.
Lucia, 13th December. Sweden, a Protestant country, celebrating the Catholic St. Lucy.
Finland, because of being occupied by Sweden for something like 700 years, celebrates Lucia too. Not quite as much, but you can still see little girls dressed up as Lucia on the 13th of December.
It's quite popular in Norway too.
The United Kingdom has no national day equivalent to Bastille day or the 4th of July. That has not stopped Hamburg from celebrating British Day every 5th and 6th of September. It is not an official holiday, but an event organized by Anglo-German societies and the community of British expatriates living in Hamburg - which itself dates back to the "English Court", a settlement of English merchants established during the reign of Queen Elizabeth I. Commercial ties date back even longer, as the Hanseatic League had established its own settlement, the Steelyard, in London during the Middle Ages. Hamburg was known as "the most English town on the continent" in the 18th and 19th centuries. Additionally, Hamburg was part of the British Zone of Occupation after World War II.
In Maine and Massachusetts, anybody will tell you that Patriots' Day is the third Monday of April, commemorating the Battle of Lexington and Concord- you know, the first battle of the American Revolution? Outside of there, people seem to think it's September 11th.
Outside of New England, not many knew about Patriots' Day until the 2013 Boston Marathon Bombing.
St. Joseph's Day (March 19) in Rhode Island is a pretty big deal. It's on par with St. Patrick's Day (which is also big in RI) in terms of celebration but it's more food oriented than St. Patrick's Day. This is due to the high Italian-American population in the state.
Rhode Island still celebrates the end of World War II long after every country involved had stopped.
What is Evacuation Day? If you live in Boston (but not smaller towns in Massachusetts), you'd know that it commemorates the day that the British evacuated the city. It's celebrated on March 17 (St. Patrick's Day) and kids get the day off from school (and, more importantly, the politicians and civil servants can glad-hand in South Boston for the annual breakfast and parade). Schools are also closed on June 17 to commemorate Bunker Hill Day in the same areas of Massachusetts.
Also Massachusetts observes Patriot's Day AKA Marathon Monday.
Everyone who was raised in San Antonio, Texas, will have had the experience of having one spring Friday, usually in April, off from school. It's called "Battle of Flowers Day" and is used to celebrate the crux of the big, city-wide ten-day festival known as "Fiesta". This daytime parade, the Battle of Flowers Parade, has been a part of San Antonio's landscape for over 100 years and is traditionally used as a celebration of springtime. Another big day of celebration in San Antonio is Martin Luther King Jr. Day, which is a day where many thousands of people gather together to march and remember the life of the late civil rights leader, who is so honored because he inspired the city's majority Latino population to fight for their own civil rights.
If you think Walmart is jumping the gun for playing Christmas songs in November, you should visit the Philippines. The De Facto Christmas season (And likewise, "The Countdown to Christmas" begins on September 1. The minute the calendar reads a '-ber' month, up come the decorations, carols and sales. And Chrismas only officially ends on January 19 (As dictated by the Church Calendar).
Easter is based upon events concerning a Middle Eastern Jew 2000 years ago. Yet it is celebrated with a (week long) fervor in Latin America that knows few equals in the world. Granted, most of Latin America is Catholic, but even the irreligious take Easter as an excuse to travel, booze it up or both.