The United States marks its 250th birthday this Fourth of July weekend, with millions expected to celebrate at barbecues, parades and fireworks displays. But before the festivities begin, many Americans will also be making last-minute shopping trips and wondering which stores will be open.While some major retailers will remain open throughout the holiday, other chains — including Costco — will close for Independence Day, and banks and government services will also be affected.This year, Independence Day falls on Saturday, July 4, while the federal holiday is officially observed on Friday, July 3. That means some government services and financial institutions will close on Friday, while many retailers will remain open throughout the weekend.Whether you’re making a last-minute grocery run, picking up barbecue supplies or need to visit the bank, here’s what you need to know.Is Costco open?Costco will not be open on July 4 — it is one of the company’s seven annual holiday closures (Getty)No. Costco will be open as usual on Friday, July 3, but all U.S. warehouses will be closed on Saturday, July 4, one of the company’s seven annual holiday closures. Is Walmart open?Yes. Walmart stores are expected to remain open during their regular business hours across both days, though customers should check with their local store for any changes. Is Target open?Yes. Target stores will generally be open on July 3 and July 4, although opening hours may vary by location. Is Trader Joe’s open?Yes, but with shorter hours on Independence Day. Trader Joe’s stores will close at 5 p.m. on July 4. Trader Joe’s is closing early at 5 p.m. on July 4 (Getty/iStock)Is Aldi open?Yes, Aldi stores will open at their normal time and close early at 4 p.m.Is Kroger open?Yes, Kroger stores and pharmacies will be open during normal business hours.Is Sam’s Club open?Yes, Sam’s Clubs will be open during normal business hours on July 3 and 4.Is Von’s open?Vons stores will be open, but pharmacies may be closed or operate with adjusted hours.Is Whole Foods open?Yes, Whole Foods stores will be open, with a majority closing early at 6 p.m.Are pharmacies open?Most CVS and Walgreens stores will remain open on Independence Day, although some locations and pharmacy hours may vary. Customers are advised to check their local store's opening hours before visiting.Are banks open?Most bank branches will be open on Friday, July 3, despite it being the federally observed holiday, but they will be closed on Saturday, July 4. Online banking and ATMs will continue to operate as normal. Customers should check with their local branch, as some locations may adjust their hours. Is the stock market open?The New York Stock Exchange is closed on July 3 and will reopen on Monday, July 6 (AFP/Getty)No. The New York Stock Exchange and Nasdaq will both be closed on Friday, July 3, in observance of Independence Day, and will reopen on Monday, July 6. Is the post office open?The United States Postal Service will operate normally on Friday, July 3, but post offices will be closed on Saturday, July 4, with no regular mail delivery. Are FedEx and UPS operating?Both delivery companies will operate modified schedules over the holiday weekend. Most standard delivery services will be suspended on July 4, though some express and critical services will continue. Customers should check with their local branch for specific holiday hours.