As of October 20, 2023, the price of a second-class stamp in the United States is not specified in the search results. However, the price of a first-class stamp is $0.66 for retail/post office rate and $0.63 for metered mail/stamps.com rate. The price of a first-class stamp was increased from $0.63 to $0.66 on July 9, 2023, which is the second increase this year and the third in the past 12 months. The price of a second-class stamp is not mentioned in the search results, but it is likely to be lower than the price of a first-class stamp.