In all instances, both before and after final rejection, in which an application is placed in condition for allowance, applicant should be notified promptly of allowability of the claims by a Notice of Allowability PTOL-37.

If there are no formal matters outstanding, you would receive a notice of allowance instead.

Once you receive the notice of allowance, there are some formalities that occur before the application is issued (granted). Notably, you must pay the issue fee within 3 months of the notice of allowance. The application will then issue around 2 months from paying that fee.

Per MPEP § 1309:

When the issue fee is paid and all other requirements have been met (e.g., drawings) for issuance as a patent, the application is then electronically exported to the Final Data Capture (FDC) stage. The FDC makes any updates necessary to the electronic file and places the allowed patent application in an issue. The average time that an allowed application is in the FDC process is 5 weeks (2 weeks of processing time for assignment of issue date). The "Issue Notification" is mailed approximately 3 weeks prior to the issue date of the patent.