This branch of the US Postal Service is located in Newport Beach on Riverside Avenue, less than a block in from the PCH in the rear strip of shops within Mariner's shopping center. Parking is available in the lot out front, but it can get tricky at busy times midday. They have a number of PO Boxes just inside the lobby which are accessible to box holders even after the actual post office hours are over. There is an automated postal center inside so that if you are just looking to purchase stamps or don't need help from a postal worker directly, you can avoid waiting in line (you can also visit the machine outside of full service hours). Greeting cards and decorative wrapping are also available for purchase in addition to standard packing and shipping supplies (boxes and envelopes, etc). All forms of payment are accepted. Express mail can be dropped off on weekdays up until 4:30, and the last daily regular mail collection is at 5:15pm.