Someone paid with me a postal money order today (the real thing, US Postal Service). Do I need to go to a post office to cash it? Can I just go to the bank?

Just deposit it in your bank. No need to go to the P.O.

Lots of places will accept those. I think even Walmart will.

Your bank will probably accept it. Other places (other than USPS) may charge a fee as they would for any other instrument. Post Office will cash it for face value, no additional charge.

As @zenvelo, says, just take it to your bank.
I think @Apparently_Im_The_Grumpy_One is correct that Walmart will cash it for @Yetanotheruser‘s mentioned fee ($3.00 under $1,000).

Back in ‘the day’, postal money orders were the gold standard on eBay. Next best thing to cash.

Same as a check – just deposit it in your bank – it’s like a ‘money order’ type payment. Your bank will verify its validity….good luck! People use those when they don’t have a bank account .

@Tag68 it’s like a ‘money order’ type payment.

It is a money order payment. That’s why it’s called a Postal Money Order.