All Nigerian regions and territories had their own individual flags and symbols in 1960. This was also the case with the new states that were created in 1967. The state flags usually consisted of the Nigerian flag, with the state coat of arms in the middle of the flag.
However, the Murtala regime (c1975) discouraged the use of state flags. This was at a time that the military regimes of the 1970s were moving us closer to a unitary system by taking over state and private owned newspapers, television stations and universities. States were instead encouraged to use the Nigerian coat of arms, placed in a circle with the name of the state around it, as their symbol.
Some states (e.g., Lagos) resumed using their pre-1975 flags and coat of arms after the return to democracy in 1979.
The return to democracy again in 1999 has emboldened more states to design new flags and symbols (e.g., Cross River, Osun and Bayelsa). Some states have resumed using their pre-1975 flags (e.g., Kano and Lagos), while some states still use their military era symbols (eg Adamawa).
This thread contains flags, coats of arms, symbols and monuments of (1) Nigerian states (2) Nigeria (3) defunct states and regions of Nigeria (4) heads of state of Nigeria
Section 4 (2) of the flags and coat of arms act is still in force.