How far from the edge of a state do you live? If the country were to split 50 ways, that would become an international border where you'd have to stop, show papers, have your vehicle be inspected, and potentially pay taxes to cross into the next state or come home. (and this wouldn't be like the easy U.S.-Canada border.)
When you go to the store, do you know where all the stuff in the stores comes from? Nearly everything probably doesn't come from the state you live in. It'd have to cross half a dozen borders if not more just to reach you. A lot of our food comes from California, and manufactured goods are shipped from Asia to the West Coast. Now, however, food and goods and medicine would have a similarly lengthy journey. The train would have to go through customs and import taxes to get into Nevada, Utah, Colorado, Kansas, Missouri, and finally into Illinois. That's pretty stupid compared to being able to it just having to cross the border once in the port in California, and then be driven without stopping the rest of the way to your local area.
Countries all have their own currencies and independent economies. The stock market in N.Y.C. wouldn't matter anymore unless you live in N.Y. State. Whatever retirement or savings you have would vaporize, since it probably isn't in the currency of your state or even located in your state. Banks would suddenly have to deal with accounts in 50 different currencies. The value of the currencies would all fluctuate dramatically for a while as it takes time to figure out exactly how worthless Mississippi and Alabama and Nebraska dollars are compared to California and N.Y. dollars. Instrest rates would go haywire and it'd be difficult and costly to sell your house or buy one if you have to move. Depending on what state you live in and what sort of industry and economic activities it has, your smartphones might stay the same price or they might become astronomically expensive along with everything else, if your state tends to import everything, because in general, the value of the currency will settle where imports balance exports. If your state has to buy (import) everything but doesn't have much to sell (export), then your currency is not going to have much value which makes exports (all the stuff from outside your state) expensive.)
(Consider Greece and Spain. They don't have much industry so they have to import a lot of stuff (sending their money out of their countries). How do they get money to come into their country? They specialize in tourism. They get people to come to them for vacations and spend their money in their countries. This might work in Hawaii and Florida. How are places like Mississippi and Alabama and West Virginia going to attract tourists? Also, being a citizen of a state means you're stuck in that state unless another state allows you to immigrate to it. You can't move to where there are jobs. So if you live in Indiana, you're sinking or swimming in Indiana.)
Business will become very difficult and a lot of jobs will be lost. Right now we're part of a 320 million person economy. The average state is like 3-5 million people. (Poland isn't on the 'booming' side of Europe, and it has 38 million people, which is bigger than even California.) So now your country, rather than being the huge and powerful U.S.A., is going to be another Iceland (without the ocean and volcanoes and beautiful scenery). Congrats!
See right now, a business only has to set up one operation somewhere in the US and has potentially 320 million customers. You can take a risk and start a business or new industry that doesn't have any customers, but you only have to find your customers as a tiny fraction of our giant market to get a toe-hold to stick around. If we become 50 separate countries, now Mr. Big European or Chinese Company will set up in only the bigger states (like California, Texas, N.Y., Illinois, Pennsylvania, Florida) because those are the only ones where it is economical to set up a business--where there are enough customers to justify the hassle of setting up a business in a foreign country.
If you're a healthcare company, you only have to get your new medicine certified and approved once and now you can sell it to 320 million people. If we're 50 countries, now you have go get your medicine approved by 50 different organizations. Or for some states, it'd probably not be practical to have many regulations, so then those states would be awash in quack medicine. Same thing with patents. You'd have to patent your new invention or improvement in 50 different patent offices. That's 50 different lawyers you'd have to pay. What if your competitor beats you to the office in a few of the states? Now you can sell your product in like Georgia, Colorado, and Virginia but not in North Carolina, Massachusetts, or Montana. Does that even make sense?
It's not just poor or rural or small states that'd do poorly. Even if you live in California or N.Y. or Texas or Florida, your great economies are going to go into the crapper as well. The finance district in Manhattan is the size of a finance district for the whole U.S.. If the rest of the U.S. isn't part of N.Y. anymore, then all of that would close, because most of it wouldn't be needed anymore, along with much of the rest of the office space going vacant. It isn't needed there in N.Y.C.. Hollywood is making movies for a 320 million person country. How many movies does a 35 million person country need? Also, now all the other states will be pushing their own industries, like their own home film companies.
Also let's say California, Texas, Florida, and N.Y. all manage to do OK. Are California and Texas going to put down the money to build and maintain a system of quality highways that run between them in the foreign countries of Arizona and New Mexico? Probably not. So now it becomes that much harder for California and Texas to do business with each other.
Internationally, foreign countries would see how much distress the various US states are in, and start to buddy up with some of them. Let's say Japan became friends with Washington and Oregon, while China became friends with California. Now you could see Japan and China fighting each other by stirring up people and trouble on our west coast - people from Oregon and California wasting time and effort fighting each other over stupid reasons that have nothing to do with any of us.
I've read some stuff about what people think would have happened if the North lost the Civil War and the South did become its own country. Some people think the ripe-to-industrialize North would have fallen in with industrial Germany, while the South would have remained close trading partners with the U.K. and France. Well, WWI was only 55 years after the Civil War. Can you imagine how horrible it'd have been if the same sort of trench warfare of WWI was fought similarly along the Mason-Dixon line? In addition to all the economic benefits of being one large country, being one large country and not fragmented keeps us all from having to fight wars with each other. The last major wars fought in North America were the Revolutionary War, the War of 1812, the Civil War, and the Mexican Revolution, and two of those were domestic wars not affecting the other countries in North America. The U.S., Canada, and Mexico, right now, in essence have a huge fortress all to ourselves that is surrounded by ocean. We are so lucky, historically speaking.
