Hello. You did not put the map that the question is referring to, which makes it impossible for it to be answered, but I can help you by showing you a concept of bias against manufacturing that can be found on maps. This can guide you to find the bias in the map you have.
A bias against manufacturing can be mute through symbols. These symbols can be used showing manufacturing activities as something harmful to the environment in which the factories are established. On the other hand, this same map may show other activities that are harmful to the environment, such as logging and cattle raising with beneficial symbols that do not imply the rejection of these economic sectors.
An example of this, manufacturing factories can be shown with symbols that refer to smoke, while logging areas can be shown with symbols that refer to tree branches.
Tree branches do not imply environmental degradation, smoke does.