Until the mid 20th century, the main economic activities were agriculture and forestry, due to large expanses of forest, the valley floors’ fertile soils and the Lerma River. Industrialization of the valley began in the 1940s, along with that of the neighboring Valley of Mexico, accelerating in the 1950s and 1960s. The population of the valley grew over four times from 1930 to 2000, with rates significant above those of the rest of the country. Today, the valley is an important industrial area with a high population density with most of the area now urbanized. The workforce of the valley changed from 60% engaged in agricultural activities in 1950 to less than 7% in 2000. Today most are employed in industry and commerce especially in Toluca metro area. Most of the remaining agricultural activity is for subsistence and seasonal, carried out only during the rainy season. The rapid change has led to environmental degradation.