In Mexico several of the monuments to the Tropic of Cancer were built at the coordinates 23 ° 27’00 “which have been considered as more than arbitrary standard for the” position “of the tropics on different maps and even in the Google Earth tool.
However, these coordinates were valid for the passage of the tropics in the year 1917, so they indicate a site that is more than a kilometer north of the current position of the tropic, which is approximately coordinates 23 26’15 “.
In a very comprehensive study of the positions of monuments to the Tropic of Cancer on Mexico’s federal highways, engineer Roberto González has found that, in addition to being found in ruins, virtually all monuments show a lag that exceeds the kilometer.
In the case of the Mexican state of San Luis Potosí with the monument of the highway 57 (perhaps the most traveled of the country) to 1.33 kms to the north of the current place of the tropic; also, a curious monument in the highway Miguel Hidalgo-Vanegas that has resisted its 120 years, with an offset of 5 kms, that is to say, the coordinates where the tropic passed in the year 1664.
A road in the state of Tamaulipas, left the chimerical monuments behind, instead there are a series of advertisements that indicate the position of the tropics during each year in a surprisingly correct way, although only correct for a particular date.
Beyond the monuments not being in the right place, the wrong thing in reality is to think that there is such a place. If the tropics move all the time, there is no such thing as a possible sign. However the importance of the information element is never less.