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I-485 (cancelled) Georgia
This 8-lane freeway would have gone from the I-85/GA 10 interchange to an interchange at the proposed I-475 at Carter Center; then north to I-285 at US 19/GA 400 (Perimeter Center). Some parts of the planned I-485 were built: GA 400 inside the beltway, and a short stub downtown that's now used for the Freedom Parkway.  
Planned in the early 1960s, it was still being fought in 1971. 
I-485 North Carolina
16.70 miles , officially, as of October 2002. But more miles have opened to traffic since then. As of Oct. 19, 2004, a 46-mile continuous stretch is helping traffic skirt Charlotte and travel among its suburbs. 
This new road, nicknamed the Outerbelt, is under construction around Charlotte. It first broke ground in the late 1980s, and some sections open to traffic are already congested. I-485 is planned to be complete around 2008, at a total cost of $1.1 billion and length of 67 miles.
Mecklenburg County N.C. Transportation Board representative Seddon "Rusty" Goode Jr. had been advocating an "outerbelt" for Charlotte since 1978. In 1988, after part of its route was selected, Goode lobbied for interstate status, either I-477 or I-485.  On July 8, 1988, Gov. James G. Martin turned the first spadeful of dirt on the 16.6-mile southern leg and announced that the road would be I-485. "I bet you thought this day would never come," he said, "but good things come to those who wait." 
On Oct. 4, 1996, AASHTO approved extending the I-485 designation, from its present terminus north of Charlotte, counterclockwise 29.7 miles to I-77 south of the city. 
In late 1989, work on the 4-level "Spaghetti" interchange at I-77 south of town started. The 1.3 mile section between US 521 and NC 51 opened on November 1, 1990.  In January 1993, a 35-mile section (unconstructed) of I-485 was named the James G. Martin Expressway. This created a bit of a flap, but not enough for Martin to decline the honor (Tobacco lobbyist and Larouchite foreign policist Jesse Helms did request that a new section of interstate near Winston-Salem not be named after himself).
In 1993, proposals surfaced to make I-485 a toll road, to speed construction of the rest of it by about 10 years; however, it lost steam later that year. On October 24, 1994, a two-mile stretch connecting the 100-foot-high I-77 interchange and South Blvd. opened, connecting the existing 1.3-mile section to I-77.  Meanwhile, plans to build a $2 billion outer-outer belt, which would go through 13 counties, were quashed by Gov. Jim Hunt, who called the idea "farfetched" and cut off funding for further study. 
In early 2000, it was expected that funding would be delayed; the EPA had cited Charlotte in violation of clean air regulations. Federal funding for highway projects in the area would be withheld until a plan is developed to improve air conditions. 
In mid-2001, the Outerbelt schedule benefited from $76 million in funding lost by two other road projects that had been delayed. If construction goes as planned, the date for completion of the entire freeway will be moved two years earlier, from 2010 to 2008. 
If construction was not delayed, Charlotte expected to have I-485 complete between I-85 to the north and I-85 to the south by July 2003. Now this is planned for October 2003. 
The 12.5-mile N.C. 49 to Lawyers Road segment suffered some vexing delays in summer 2003. Originally planned for July, the opening date slipped three times because of rain and equipment problems. A portion opened in September and the rest opened in November (see "Ribbon Cuttings", below).
To try for clarity, I've added directions like [S] for the southern end, to differentiate between highways that intersect I-485 twice.
We built it, and they came
By 1997, I-485 traffic was already overwhelming sections of the 4-lane road. Drivers were screaming for 6 or 8 lanes, and planners planned to build most remaining sections with 6 lanes.  The diamond interchange at NC 16 (Providence Rd) has already been revised, with loop ramps added. 
In early 2004, it became apparent that many present and future stretches of I-485, along with connecting highways, would be overwhelmed with traffic greater than expected. Officials in the Charlotte area and at NCDOT are pointing fingers over a highway that was, in hindsight, underdesigned.
For example, county commissioners originally told NCDOT that I-485 in the southeast would pass through rural areas and have low traffic. Accordingly, the state built a four-lane highway that most now agree should have had eight lanes. Without pinning the blame on one agency, one can see that fast growth in the area outpaced the necessarily longer design and build cycle. 
Other Charlotte Observer articles for I-485: