Section 17.100.020 of the Fort Bragg Municipal Code defines political signs as follows:
Political or Social Issue Sign. A sign that addresses: a. The passage or defeat of a measure appearing on the ballot in any national, state, or local election; b. The election or defeat of any candidate for any public office in any national, state, or local election; or c. An international, national, state, or local political or social issue.
Political Signs are governed by Fort Bragg Municipal Code Sections 17.38.040(C)(4) and 18.38.040(C)(4). Those regulations are excerpted here: Political Sign Regulations (PDF).
To determine whether your sign is located on property in the Coastal Zone or Inland Zone, see the City's Zoning Map (PDF).