On February 15, 1841 Joseph Smith signed an authorization for Hyrum Smith and Isaac Garland to act as agents for the church. Among other things the authorization mentions that Nauvoo was “the corner stone of Zion.” JSP, Documents Vol. 8, page 46.
In a letter to the saints abroad, published May 24, 1841, Joseph urged all saints to gather to Nauvoo, Illinois “without delay.” It said, “This is important, and should be attended to by all who feel an interest in the prosperity of this the corner stone of Zion.” Id., p. 156.
To make the point that Nauvoo was where the saints were to gather as the center point, the letter announced that all stakes were dissolved, excepting only the ones in Nauvoo and across the Mississippi River in Iowa:
“Let it therefore be understood, that all the stakes, excepting those in this country, and in Lee county, Iowa, are discontinued, and the saints instructed to settle in this county as soon as circumstances will permit.” Id.
Of course, three years later locations were changing again. Joseph looked much further westward to establish the center stake and corner stone for Zion. Somewhere in the western Rocky Mountains where a New Jerusalem would be built. Joseph was slain before he could take that journey. Therefore, that location has yet to be revealed.