Mexican Spanish () is the variety of dialects and sociolects of the Spanish language spoken in the United Mexican States. Mexico has the largest number of Spanish speakers, with more than twice as many as in any other country in the world. Spanish is spoken by just over 99.2% of the population, being the mother tongue of 93.8% and the second language of 5.4%. Variation The territory of contemporary Mexico is not coextensive with what might be termed Mexican Spanish, since linguistic boundaries rarely coincide with political ones. The Spanish spoken in the southernmost state of Chiapas, bordering Guatemala, resembles the variety of Central American Spanish spoken in that country, where is used. Meanwhile, the Treaty of Guadalupe Hidalgo led to a large number of Mexicans residing in what had become US territory, and many of their descendants have continued to speak Spanish. In addition, the waves of 19th- and 20th-century migration from Mexico to the United States, have contributed greatly to making Mexican Spanish the most widely spoken variety of Spanish in the United States. Finally, the Spanish spoken in coastal areas often exhibits certain phonetic traits in common with the Caribbean rather than with that of central Mexico, and the Spanish of the Yucatán Peninsula is quite distinct from other varieties. It should also be noted that there is great variation in intonation patterns from region to region within Mexico. For instance, the Spanish of northern Mexico, including the traditional Spanish of New Mexico, is characterized by its own distinct set of intonation patterns. Regarding the evolution of the Spanish spoken in Mexico, the Swedish linguist Bertil Malmberg points out that in Central Mexican Spanish—unlike most varieties in the other Spanish-speaking countries—the vowels lose strength, while consonants are fully pronounced. Malmberg attributes this to a Nahuatl substratum, as part of a broader cultural phenomenon that preserves aspects of indigenous culture through place names of Nahuatl origin, statues that commemorate Aztec rulers, etc. The Mexican linguist Juan M. Lope Blanch, however, finds similar weakening of vowels in regions of several other Spanish-speaking countries; he also finds no similarity between the vowel behavior of Nahuatl and that of Central Mexican Spanish; and thirdly, he finds Nahuatl syllable structure no more complex than that of Spanish. Furthermore, Nahuatl is not alone as a possible influence, as there are currently more than 90 native languages spoken in Mexico. Phonology Consonants Affricates Due