Good Friday is an important religious observance among many Christians, but it is not a federal holiday. That means the answer to "Is the post office open on good Friday?" is "most definitely." With a few exceptions, most public offices and publicly regulated institutions, such as banks, are open for business. Here is a short guide to what's open, what's not, and what's iffy.
The United States Post Office: The post office may be contemplating closing on Saturdays, but it is most definitely open this Friday. The post office closes only for the 11 federal holidays (Christmas is the only religious holiday on the list of 11.) Mail is being picked up and delivered, too.
Banks: The Federal Reserve Board is open Friday, so your bank probably is, too. If a bank's deposits are insured by the FDIC (Federal Deposit Insurance Corp.), as is the case for most banks, federal holiday rules apply.
New York Stock Exchange: The New York Stock Exchange is not trading on Friday. It is a private entity and has been closed on Good Friday since 1885 (with three exceptions), according to the NYSE official history on its website. Legend has it that after the Panic of 1907, which fell on Good Friday and when the stock market lost a third of its value, the NYSE has been closed on Good Friday, according to a 2008 Houston Chronicle report.
Businesses: Most but not all businesses are open. Some are open for the morning but close at noon or the early afternoon. The hours of private businesses, such as dry cleaners and grocery stores, are set by the owners.
Schools: Many K-12 schools are on spring break and closed anyway. Among public schools not on break, some are open and some are not. In Louisville, Ky., for instance, most public schools are open. In Boston, public schools are closed. A random survey of five public universities found all to be open. Check the academic calendar before heading off to class.
Government services: Federal government facilities are open. Offices of state and local governments vary; it's best to call ahead if you plan to visit a state or local agency.