The Turnpike itself has two sections. The first is the Mainline, a route from the Golden Glades Interchange (north of Miami) to Wildwood. This has the hidden designation of State Road 91 (SR 91). It was opened in stages between 1957 and 1964. The second is the long Homestead Extension of Florida's Turnpike (HEFT). This was completed in 1974. Its hidden designation is State Road 821 (SR 821). This runs from Florida City (near Homestead) through the suburbs to the west and north of Miami, connecting to the Mainline four miles (6 km) north of the Golden Glades Interchange. Florida's Turnpike is considered one of the busiest highways in the country (according to the IBBTA, the highway is the nation's 3rd most heavily traveled toll road).