The biggest part of our brain, the cerebrum is separated into two halves, the left and the right hemisphere by a deep groove that is called the l<span>ongitudinal fissure or</span> cerebral fissure.
The hemispheres are connected by a bundle of nerve fibers called the corpus callosum in order to enable communication between the two of them, as their communication is necessary for various cognitive functions of the brain.
I would say an "Altitude Tint Map" or a "Mercator Projection Map".
Hope this helped!
One explanation could be the differences in climate (environmental factors). The climate in northern Mexico could support the reproduction of the mosquito species, which is a vector of the dengue virus. Other environmental conditions that influence its endemicity could include living conditions and sanitation. The other possiblity could be that the people in the US have developed immunity for the disease, therefore, are unaffected even when infected by the virus.