An unused highway may reference a highway or highway ramp that was partially or fully constructed but was unused or later closed. An unused ramp can be referred to as a stub ramp,stub street,stub-out, or simply stub.
Arizona State Route 153 (SR 153) is the former designation for what is now South 44th Street on the southeast part of town. It traveled north from University Drive to Washington Street, just east of Phoenix Sky Harbor International Airport. It was designated in 1992, taking over the former routing of SR 143 from the airport north with a new Salt River crossing constructed on a new alignment to the south. SR 153 was planned to travel south and west from University Drive to the 40th Street corridor and interchange with Interstate 10 (I-10) by the end of 2007, providing east side, freeway access to the airport from I-10. This left mainline stubs at the former southern terminus. (33°25′31″N111°59′01″W / 33.425415°N 111.983719°W / 33.425415; -111.983719) After constant delays, SR 153 was removed from the state highway system in 2007 and the temporary airport access from SR 143 became permanent. All traffic south of the airport now travels in the northbound lanes, with the southbound bridge shut off.
About 2 miles away from the intersection of Interstate 540 and US 71, there is a unused stretch of highway. It currently ends at Route 255 and 22, about 4 miles away. It is unknown what this stretch of pavement is for, maybe possible for Future Interstate 49.
Red Mill Road south of DE 2 bypasses a short segment of road over White Clay Creek. The abandoned stretch of road is very narrow and contains two bridges over small channels that served a mill. The area is flood prone due to its proximity to the creek. The northern and southern ends of the bypassed road is used for residential purposes, with the two segments being connected by a footbridge.(39°41′31″N75°42′29″W / 39.691957°N 75.70792°W / 39.691957; -75.70792)
The entire stretch of Harmony Road between DE 4 and DE 2 was relocated from its original alignment to a new alignment to the west. The relocation resulted in four fragments being left behind, divided by rail lines or White Clay Creek. An abandoned bridge lies over the creek, but nothing crosses the rail lines. The four segments are used for residential purposes and are labeled Old Harmony Road on some maps. (39°41′42″N75°41′33″W / 39.695003°N 75.692374°W / 39.695003; -75.692374)
Near Hartsfield–Jackson Atlanta International Airport, two ramp stubs exist at the Virginia Avenue overpass above Hartsfield Drive. Hartsfield Drive carried traffic into the Atlanta Municipal Airport Terminal before the construction of the present terminals. These ramps were part of four ramps leading to and from Virginia Avenue, which linked the terminal to I-85 south and to the local communities. Originally, the four ramps consisted of a diamond ramp that linked northbound Hartsfield Drive to eastbound Virginia Avenue (still visible), a diamond ramp that linked eastbound Virginia Avenue to southbound Hartsfield Drive (still visible), a cloverleaf ramp that linked northbound Hartsfield Drive to westbound Virginia Avenue (destroyed), and a cloverleaf ramp that linked westbound Virginia Avenue to southbound Hartsfield Drive (destroyed).
The stub of an as-yet unbuilt flyover ramp from I-75 northbound to I-285 westbound on the northwest side in Cobb County. According to GDOT, the ramp may eventually be used as part of a revamp of the interchange.
The western end of the freeway portion of SR 14 Spur was relocated as part of the construction of the South Fulton Parkway. This realignment closed what had been the western end of the freeway. This alignment exists as ramp stubs from Roosevelt Highway at its intersection with Welcome All Road. The ramps depart the intersection to the north and curve toward the east but stop short of intersecting South Fulton Parkway at its Roosevelt Highway interchange. A look at the old configuration.
The freeway portion of SR 372, where it intersects SR 5 Business, ends in stub ramps on the mainline. A half diamond interchange links the freeway to SR 5 Business. The freeway section consists of the western end of SR 372 and the freeway was constructed as a part of SR 400, which was at one time proposed to connect with SR 515.
I-185 has a northern terminus east of the city at I-85. However, short stubs exist on the mainline of I-185 on both the north and the south sides. They are part of a proposal to extend the freeway north to Hogansville and possibly even further north to Rome via the U.S. Route 27 (US 27) corridor.
There are stubs and grading in the median of Interstate 72 northwest of the city for a planned but never built connection with Interstate 39. There is also grading north of this proposed interchange where crops are no longer planted. 
The continued development on the southeast corner of Halsted St and 63rd St near the Englewood Shopping Center led to the near-full demolition of the Halsted Parkway , among other streets in the area, as shown on this Google map . The road was fully demolished until its intersection with 63rd St. The only remnants of the demolished part of the street are small slabs of pavement on a walkway (Which once was a small section of 64th St.), and the curved edges on some of the parking lots. The only fully remaining parts of the parkway have since been realigned and renamed 63rd Parkway.
At the northern end of Illinois Route 6 (an extension of Interstate 474), there is an interchange in which all northbound traffic is diverted to Illinois Route 29 and the freeway begins for traffic going southbound. Currently, the main traffic lanes extend north past the intersection and a southbound-to-eastbound exit exists (but does not connect to the mainline, yet ). All ramps leading to and from the traffic lanes north of the intersection are present, though the westbound-to-northbound ramp does not yet connect, either. There are plans to extend Illinois Route 6 north beyond Chillicothe to Interstate 180 as Illinois Route 29.
East of Interstate 474 at the New Farmington Road/Maxwell Connector interchange, stubs exist on the mainline. The expressway west of the interstate is slated to eventually carry Illinois Route 336. However, the only part finished is a short stretch connecting I-474 with Maxwell Road to the west. The freeway continues past the completed ramps to I-474, but is closed and just dies in the grass. The Illinois Department of Transportation does not have the road continuing east of I-474 as of right now. 
The Wallenberg Expressway (originally known as the Woodruff Expressway) was designed in the 1970s to go northward at the interchage of Interstate 39 and U.S. Route 20 into downtown Rockford. The highway would have been built northwest along Woodruff Avenue in Rockford but was axed due to community opposition. As a result of the road being cancelled, a short stub exists where the mainline would be coming from the north.  North of the stub, grading exists for the road, as well as a cloverleaf ramp that was to go to northbound I-39 and eastbound U.S. 20 and a ramp to westbound U.S. 20. The only part of the road built is now a ramp from I-39 to westbound U.S. 20. The ramp has an extra wide shoulder, the result of combining the former mainline and the ramp, and grading for a cloverleaf ramp from eastbound U.S. 20 to the road that was to go north also exists. 
Exit 238 on Interstate 55 for Illinois Route 129 was formerly an interchange with full access until 2012 when the deteriorated overpass for the southbound exit was closed and removed, leaving only a northbound exit and entrance (a U-turn ramp, also demolished, helped northbound IL 129 access southbound I-55). The southbound exit ramp and U-turn ramp gradings still remain and the latest Google map shows the overpass supports are still standing. There are plans to make the interchange full access once again, most likely coinciding with the Illiana Corridor Project. 
The Cumberland Parkway ends at US 27.  Grading is present to show an eventual complete partial cloverleaf interchange and an extension of the mainline eastward. This route is designated as part of the Future I-66 Corridor, which outlines a plan for the parkway to extend east into West Virginia. The parkway formerly went due east into the city center but 3.67 mi (5.91 km) of mainline going northeast and two interchanges were built to avoid traffic signals and cross-traffic in preparation for Interstate status. Former alignment The former alignment is now KY 80 and KY 6014 on maps.
The northern terminus of I-49 at the I-20 interchange contains numerous stub ramps that indicated a previously designed northern extension. As early as 1999, this idea was scrapped with the adoption of the Future 49/High Priority Corridor 1, a plan to extend I-49 to Kansas City. It was due to high costs in acquiring right of way and community opposition. This plan would route I-49 onto LA 3132 south of the city. There are talks to turn the stretch of I-49 from LA 3132 north to its northern terminus into I-149. (32°29′47″N93°45′34″W / 32.49646°N 93.75943°W / 32.49646; -93.75943)
I-310 ends at US 90 west of the city. Originally, I-410 (The Dixie Freeway) was to be the southern bypass of New Orleans and connect what are now I-310 and I-510, but it was cancelled in 1977 due to environmental lawsuits and the miles were transferred to I-49. However, when it was built, mainline stubs were built at the southern terminus in the hope that a continuation would eventually be built. These stubs will be utilized when I-49 is extended to New Orleans, as the current plan has I-49 routed just south of the I-310/US 90 interchange. (29°53′57″N90°23′58″W / 29.899182°N 90.399467°W / 29.899182; -90.399467)
Interstate 195 (I-195) has an interchange with the I-95 (Maine Turnpike) at its western terminus. As originally constructed, both ramps were cloverleaf ramps, but subsequently, the cloverleaf ramp handling traffic exiting the turnpike was replaced between 1988 and 1998, turning the interchange into a trumpet. The grade for the original cloverleaf ramp remains. Also, the eastbound ramp from the turnpike crosses a bridge meant for two lanes, but only has one and shifts over to the left. (43°31′39″N70°27′09″W / 43.527541°N 70.452565°W / 43.527541; -70.452565)
Interstate 335 (I-335), a spur of I-35W, was proposed to connect I-35W with I-94 just north of downtown. The project got as far as right-of-way acquisition and grading for and paving of exit ramps at the east end on I-35W before it was cancelled due to local opposition. The southbound lanes of I-35W contain the vestiges of an entrance ramp from I-335 and a ramp to I-335 from the northbound lanes is visible despite having been demolished. Both are near the Hennepin Avenue overpass. (44°59′30″N93°14′10″W / 44.991596°N 93.236026°W / 44.991596; -93.236026) North of this, the other half of the proposed full interchange is also visible. The exit from I-35W south to I-335 west is still graded and a stub of pavement that still exists was to be the ramp from I-335 east to I-35W north. (44°59′46″N93°14′16″W / 44.996034°N 93.237888°W / 44.996034; -93.237888) A northbound exit from I-35W to Johnson Street makes a rather long dogleg that would have accommodated this ramp and the redundant Johnson Street exits support an I-335 merge. In the same area, a pavement stub existed in the I-35W median but has since been removed.
A proposed Route 755 was to start at I-44 at its interchange with I-55 and connect to I-70, interchanging with I-64/US 40. The freeway would have looped to the west of downtown. Indications of the cancelled freeway can be seen in old satellite images, showing a pavement stub on the Lafayette Avenue exit ramp that has since been removed. There is also blocked off lane on eastbound I-44 that would have been a ramp to northbound Route 755. It was to follow Grattan Street, but since the freeway's cancellation, it and Grattan have mostly been replaced by Truman Parkway. Ramp stubs can also be seen around the exits for 20th, Chestnut, and Market Streets from I-64. (38°37′40″N90°12′42″W / 38.627834°N 90.211744°W / 38.627834; -90.211744). A sufficiently large right of way is present there as well.
Because of the construction of new Busch Stadium, the 8th Street on-ramp to eastbound I-64 was demolished, leaving a ramp stub on the Interstate. It is not viewable from the air because of the elevated freeway design downtown, but can be seen while driving. It was a left-entry ramp. The old ramp design can still be seen on a Microsoft Research maps satellite image.
Spring Avenue once had a viaduct over a rail yard that connected Forest Park Avenue with Gratiot Street. The viaduct was closed and partially demolished sometime after 1991 (and perhaps even after 1998). The south end is barricaded by a mound of gravel and the vegetation is overgrown. The north end is blocked by a fence, followed by semi trailers and jersey barriers. Between I-64 and where Scott Avenue would intersect Spring, the viaduct has been demolished and Spring exists as an at-grade street off of Market Street. The remaining elevated roadway has been demolished. (38°37′46″N90°14′18″W / 38.629519°N 90.238277°W / 38.629519; -90.238277)
The MacArthur Bridge formerly carried traffic across the Mississippi River starting 1917, carrying US 66 and US 460 at times. Due to deterioration, the bridge was closed to automobile traffic in 1981, though trains still use the bridge today. Some of the connections were demolished, including the approach in Illinois, though an unused bridge frame and wide supports still stand. Remnants of approaches are used as a parking lot on the west side or are just shut off from traffic by jersey barriers (Note that as of March 2012 the parking area was rebuilt and the remnant removed, the image herein has not been updated). Pavement still exists on the bridge, though only up to the Illinois side.
PR-22 was ended on PR-866/PR-855 intersection before the Arecibo extension, after this extension, the former PR-22 was modified, leaving a graded ramp and small pavement stub on PR-22 eastbound on-ramp. 
West of the old Río Piedras State Penitentiary, the Americas Expressway (signed as PR-18) has a ramp stub at the interchange with PR-21 from PR-21 eastbound to PR-18 northbound, because it was removed by the construction of the reversible lanes ( and ), and south of the interchange, there is an unused overpass bridge .
I-86 was planned, in 1968, to connect Hartford and Providence. It was cancelled in 1982 because of the impending impact on the nearby Scituate Reservoir but there is an indication as to where it was to enter the Providence area. Exits 6A-B for US 6 on I-295 was where I-84 was planned to intersect the partial beltway, with stubs on the US 6 mainline and ramp and flyover grading indicating this. There is also a stub on US 6 to northbound I-295 for the unbuilt flyover. A ramp from I-295 north (exit 6B) that was to go to westbound I-84 has been converted into a turnaround ramp (I-295 north to I-295 south). (41°49′15″N71°30′46″W / 41.820775°N 71.512649°W / 41.820775; -71.512649)
There is a stub off ramp from I-195 westbound where exit 1 used to be. It used to carry traffic into the heart of the financial/court district in 2002. As of November 2008, there were still signs posted for it. It is being used occasionally for staging of construction vehicles working on the new I-195/I-95 connection realignment project. 
There used to be an exit 66 on Interstate 90 (I-90) east of Rapid City for Box Elder and the Ellsworth Air Force Base. This exit was closed on October 1, 2003, and the pavement ripped up. A new interchange (exit 67) opened a few months earlier that supplanted it. This exit is for Liberty Boulevard, which leads right to the gates of the Air Force Base. Local officials feared the potential closing of the base and successfully lobbied the state and federal government to construct a new interchange. The exit change will also help keep commercial development away from the runways. While the pavement is gone, one can see grading outlining the old ramps. (44°07′04″N103°04′11″W / 44.117832°N 103.069739°W / 44.117832; -103.069739)
A stub ramp exists at the I-40/I-240 interchange in East Memphis.  It will eventually allow for a two-lane flyover for I-40 westbound to continue through the interchange, relieving the current one-lane ramp of the increased traffic in the region. A corresponding flyover in the eastbound direction will also be built (this will be the fourth level of the interchange) and replace the existing one-lane ramp. In addition, grading remains as the remnant from a loop ramp from westbound I-40 to westbound I-240 which was destroyed after a two-lane flyover replaced it.
At the intersection of I-55 and US-51 (Elvis Presley Boulevard), a loop ramp has been eliminated. The ramp ran from northbound I-55 to southbound US-51 and was eliminated during the widening of I-55 in 2001 due to weaving conflicts with an on-ramp from Brooks Road immediately before the loop. (35°03′50″N90°01′24″W / 35.064024°N 90.0234°W / 35.064024; -90.0234)
Similarly, a loop ramp from northbound I-55 to westbound SR-17/Shelby Drive was eliminated as part of the widening. 
There is a freeway stub at the western end of SR-840.  The high costs of going through hilly land and the recession have put the plan for a northern loop on hold, but it might be, in the future, designated "I-840." An entire loop would be about 178 mi (286 km) long.
The proposed Stadium Freeway was to have a southern terminus at I-43/I-894 in southern Milwaukee. While the freeway was never built south of National Ave, a graded ramp exists just east of W. Loomis Rd. The ramp was to come from I-43/I-894 eastbound going north. It was a complete interchange, but one ramp was demolished (it appears it was a flyover as the top level) and there is a hint of a left-exit ramp just west of the proposed interchange. Other ramps exist at this unusually wide interchange and lead to and from a park and ride lot. In 2011 the lower half of the park & ride and all exit ramps were shut off to public traffic and were made available to highway construction traffic only (for the I-94 North–South Freeway Project). With the closing of the west-bound I-94 off-ramp towards the park & Ride, a new off-ramp was constructed that leads to Loomis Road northbound. This required the removal of the on-ramp from the park & ride headed towards east-bound I-94. (42°57′45″N87°57′48″W / 42.962382°N 87.963227°W / 42.962382; -87.963227)
US 12 abruptly ends at Wisconsin Highway 67 (WIS 67) just north of the city. Northbound lanes must exit and the mainline continues for about 50 yards (46 m). Southbound lanes actually utilize an underpass that was built to carry US 12 northwest toward Whitewater. More unused pavement exists as a never completed on-ramp from southbound US 12 to WIS 67 and an on-ramp (broken up by the operational "flyunder" ramp) from WIS 67 to northbound US 12. Grading is evident on the west side of the interchange. The unbuilt expressway was to be part of a Madison to Chicago route that was limited by Illinois' participation. (42°41′54″N88°32′28″W / 42.698349°N 88.541243°W / 42.698349; -88.541243)
The southern terminus of the Interstate-quality US 12 ends just east of the city. Southbound lanes exit onto a ramp with an interchange with WIS 120. Northbound lanes merge onto a stub just before a Welcome to Wisconsin rest area. US 12 was to be a part of a fully controlled access freeway from Madison to Chicago, with a connection to the Illinois Tollway System at the state line. There is grading south of the interchange as well. (42°29′53″N88°18′56″W / 42.498159°N 88.315423°W / 42.498159; -88.315423)
North of the city, at the Lincoln–Oneida county line, US 51 loses its freeway status and continues north as a two-lane highway. (45°33′39″N89°40′18″W / 45.560789°N 89.671619°W / 45.560789; -89.671619) After a lane drop approaching the end of the freeway, the northbound travel lane is shunted through the median while a northbound pavement stub exists before dying in the grass, indicating a possible extension north, however there are no plans to do so in the near future.
Staff (1998). "H.R. 0686". Iowa House of Representatives. House File 686. 77th General Assembly.
Petition Response Section, Exposure Investigation and Consultation Branch, Division of Health Assessment and Consultation, Agency for Toxic Substances and Disease Registry (November 17, 1999). Petitioned Public Health Assessment (Report). New York City: Centers for Disease Control. Retrieved January 15, 2007.