By Pat Loeb

PHILADELPHIA (CBS) — Philadelphia is on track to become the first place in the United States to achieve “World Heritage City” status.

There are more than 230 World Heritage cities around the globe, but none so far in the US.

Philadelphia, though, has the special status of “observer member,” and applied, more than a year ago, to become a full member of the group.

And, on a recent trip to Mexico, Mayor Nutter did some lobbying to get the city designated as such.

It was on the mayor’s agenda when he visited two World Heritage cities in Mexico: Mexico City and Puebla.  He says the  mayors of both those cities promised to support the application.

And the Mexico City mayor went a step further, Nutter recalls:

“He subsequently used apparently the most used form of communication in the universe — Twitter — to express his support for Philadelphia reaching that status.”

The organization of World Heritage Cities’ congress could decide at its next world congress meeting in November.