Excessive sun exposure is a common cause of brown spots on the scalp due to conditions such as melasma and actinic keratosis, per the Mayo Clinic and the American Academy of Dermatology. While these conditions differ slightly from each other, they both are frequently caused by excessive ultraviolet radiation. Continue Reading.
Mexico is a part of North America. Maybe you are thinking of Northern America, which is a tricky area as sometimes Mexico is included and sometimes it is not. Northern America â¦ is the northern portion of North America, in which Canada and the United States are usually the two sole members.
Administrative divisions of Mexico. The United Mexican States (Spanish: Estados Unidos Mexicanos) is a federal republic composed of 31 states and the capital, Mexico City, an autonomous entity on par with the states. According to the Constitution of 1917, the states of the federation are free and sovereign. Each state has its own congress and constitution.