Road and rail for trade with the US, 1996: Instituto Mexicano del Transporte. The Instituto Mexicano del Transporte (IMT) estimated the figures based on data provided by the Secretaría de Comercio y Fomento Industrial in Mexico and the Bureau of Transportation Statistics in the United States. For 1995, the IMT estimates that 4,023 million tons were exported from Mexico to the north, and 11,005 million tons were imported into Mexico from the north. The United States was the origin and destination of the vast majority of these shipments, although some shipments originated in, or were destined for, Canada. There is no way of quantifying the specific proportion allocated to Canada versus the United States.
For 1996, 5,482 million tons were exported from Mexico to the north by rail. Of this, 4,813 million tons were shipped to the United States. The remaining 669 million tons were either shipped to Canada or (although originating in Mexico as rail shipments) were ultimately transshipped via air or sea through U.S. or Canadian ports. Also in 1996, 12,933 million tons were imported into Mexico from the north by rail. Of this, 10,307 million tons came from the United States. The remaining 2,626 million tons came either from Canada or from a third country, but reached Mexico as transshipment from Canadian or U.S. ports.
Air: The information in imports and exports of cargo transported by air to the United States and Canada, is collected through the monthly reports by city origin – destination, developed by national and international airlines.
By 2008, the information covered 90 cities in North America, of which 19 corresponded to Canada, and 71 to the U.S., which in total cover by air on 55.9% of total international trade of Mexico with respect to the world.
Method of calculation: Since information is reported by city origin – destination, exports are calculated by locating the country which has the destination city, and on the other hand, the country of origin city in this case is Mexico. Subsequently, this includes a sum of tonnes transported from the country of origin. To calculate import happens in reverse. The unit of measurement is recorded in kilograms, without specifying the type of goods transported, and for the presentation of information in this format, is done through the division of 1, 000,000 to bring in “thousands of tonnes”.
Maritime: Data on cargo transportation by sea trade is published monthly by the Dirección General de Puertos of the Secretaría de Comunicaciones y Transportes. Cargo volume is expressed in metric tons, this information does not include the weight of full or empty containers. The integration of information is done via the formats of monthly port movement provided by Administraciones Portuarias Integrales based on their records of operation and Capitanías de Puertos on information from the formalities for entry and departure of ships arriving to ports in Mexico.