Have you ever wondered why Salt Lake City addresses sound like math coordinates? It’s because they are. Salt Lake City is laid out in a grid, with a center point at the intersection of a base line (running east-west) and a meridian (running north-south). But how did that center point get decided?
Four days after Brigham Young arrived in the Salt Lake Valley, he touched his cane to the ground and said, “Here we will build the temple of our God.” Orson Pratt and Henry Sherwood, tasked with surveying the land and laying out the city, chose a location near this spot to be the base and meridian location. This spot is at the corner of what is now South Temple Street and Main Street, or the southeast corner of Temple Square, making the temple the physical and spiritual center of the city. This spot also became the reference point for land surveys from Ogden to St. George.
This pink sandstone marker was placed on the center point in 1855. After more than 130 years of freezing and thawing, the marker had deteriorated significantly. In order to preserve the stone, the Church History Museum, with the encouragement of city officials, replaced it with a replica carved from the same local sandstone in August 1989.
It should be noted that Orson Pratt made his observations based on solar time, determining the meridian to be longitude 111 degrees, 26 minutes, 34 seconds west of Greenwich. A later survey using more exact methods showed that Pratt's measurements were about 27 minutes in error. A second marker was placed on the correct spot, just north of the South Visitors’ Center at Temple Square.