sentences:  From 1940 to 1970 GDP increased sixfold while the population only doubled, and peso-dollar parity was maintained at a stable exchange rate.Economic nationalist and protectionist policies implemented in the 1930s effectively closed off Mexico to foreign trade and speculation, so that the economy was fueled primarily by state investment and businesses were heavily reliant on government contracts.As a result of these policies, Mexico's capitalist impulses were channeled into massive industrial development and social welfare programs, which helped to urbanize the mostly-agrarian country, funded generous welfare subsidies for the working class, and fueled considerable advances in communication and transportation infrastructure.