established. 20th century Throughout the twentieth century, seeing growth in its industrial, tourist, and service industries, Guadalajara began a period of rapid transformation into the metropolis it is today. The city would gain the second largest economy in Mexico, following only by Mexico City. After the Mexican Revolution of 1910, Guadalajara became the second most populous city in the country. However, the decades that followed brought a number of regional wars in the states of Jalisco, Michoacán, and Guanajuato. The aftermath of the Great Depression took a further toll on the city. Fortunately, by the 1940s the city would experience industrial, demographic, and trade growth. In 1910, the Mexican Revolution began, bringing an end to the Porfiriato. With conflict concentrated in the capital, Guadalajara experienced relative calm. After the Cristero Conflict, peace returned to Guadalajara and the city flourished, outgrowing its colonial roots. This period saw the birth of new schools of architecture that would decorate the city from the 1920s to the 1980s. Guadalajara again experienced substantial growth after the 1930s, and the first industrial park was established in 1947. Its population surpassed one million in 1964, and by the 1970s it was Mexico's second-largest city and the largest in western Mexico. Most of the modern city's urbanization took place between the 1940s and the 1980s, with the population doubling every ten years until it stood at 2.5 million in 1980. The population of the municipality has stagnated, and even declined, slowly but steadily, since the early 1990s. The increase in population brought with it an increase in the size of what is now called Greater Guadalajara, rather than an increase in the population density of the city. Migrants coming into Guadalajara from the 1940s to the 1980s were mostly from rural areas and lived in the city center until they had enough money to buy property. This property was generally bought in the edges of the city, which were urbanizing into fraccionamientos, or residential areas. In the 1980s, it was described as a "divided city" east to west based on socioeconomic class. Since then, the city has evolved into four sectors, which are still more or less class-centered. The upper classes tend to live in Hidalgo and Juárez in the northwest and southwest, while the lower classes tend to live in the city center, Libertad in the northeast, and southeast in Reforma. However, lower class development has expanded