Md. Code, Land Use § 5–101

(a) Except as provided in subsection (b) of this section, the territorial jurisdiction of a planning commission over a subdivision is limited to land located in the local jurisdiction.

(b) In a local jurisdiction where a county has not adopted subdivision regulations, the territorial jurisdiction of a planning commission of a municipal corporation may include all land located up to 1 mile beyond the corporate limits of the municipal corporation that is not located in any other municipal corporation.