The fund will normally invest at least 90% of its total assets in investment-grade municipal securities (rated in one of the four highest rating categories assigned by established credit rating agencies) by at least one major credit rating agency or, if unrated, deemed by T. Rowe Price to be of comparable quality. The fund may invest up to 10% of the fund's total assets in below investment-grade bonds, known as "junk" bonds, including those with the lowest credit ratings.