List of gaps in Interstate Highways

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For the most part, the United States Interstate Highway System is a connected system, with most roads completed. However, some Interstates have gaps. There are several cases covered here:

  • True gaps, where two sections of road are intended to be part of the same Interstate, but the two sections are not physically connected, or are only connected by non-Interstates, or are connected but the connection is not signed as part of the highway
  • Freeway gaps, where the Interstate is signed as a continuous route, but part or all of it is not up to freeway standards; this includes drawbridges, where traffic on the Interstate can be stopped by boats
  • Connection gaps, where a three-digit Interstate does not connect to its two-digit parent via a freeway-standard connection

Not covered here are a few other cases worth mentioning:

  • Gaps in Interstate Highway standards, such as shoulder widths and bridge clearances, since these are too frequent
  • Two-digit Interstate numbers which are meant to be repeated, one on each side of the country, namely I-76, I-84, I-86 and I-88
  • Gaps on the Interstates in Alaska and Puerto Rico, since those are not held to the same standards
  • Places where Interstates cross but don't connect via a freeway-standard connection (e.g. I-84 and I-87).
  • Places where a three-digit Interstate connects to its parent via another three-digit Interstate of the same parent; the numbering system allows for this
  • Sometimes, near toll booths (e.g. Mackinac Bridge toll booth), a brief segment of the Interstate will have a median break with a double-yellow line but have at least 4 lanes total (i.e. Super-4).

Contents

True gaps

  • I-39 had a gap between Rockford, Illinois and Portage, Wisconsin until the late 1990s, when signage was added along I-90 to fill the gap.
  • I-74 currently has three sections, one heading west from Cincinnati, Ohio, one from the Virginia/North Carolina state line along I-77 south along I-77 and east to a point southeast of Mount Airy, North Carolina, and one concurrent with the only section of I-73, from Emery, North Carolina to Ulah, North Carolina. Other sections up to freeway standards are signed with I-74 shields that have FUTURE instead of INTERSTATE. Future I-73 shields are also placed along some of these sections, but only one section of I-73 is signed with normal Interstate shields.
  • I-90. Many believe that there is presently a gap in I-90 at the Chicago Skyway, but there is controversy and confusion surrounding this issue. Historically the skyway was commonly considered to be, and was signed as, part of I-90. However, around 1999 the City of Chicago, Illinois determined it may never have applied for approval to sign it as an Interstate. (It also is not designed to Interstate standards.) The city resigned the skyway, and it is now mostly posted with "TO I-90" signs, with a few older signs remaining. Because of this development, it has been widely circulated, especially among road buffs, that there is now a gap in I-90. However, the Illinois Department of Transportation has always and continues to report the skyway as part of the Interstate system, and the Federal Highway Administration still considers it as such. A FHWA legal memo says "There is no doubt about it. The Chicago Skyway is officially part of I-90 that (has) always been included in the Dwight D. Eisenhower National System of Interstate and Defense Highways." [1][2]
  • I-93 historically has had a gap through Franconia Notch State Park in northern New Hampshire. The road filling the gap, a section of US 3, is built to freeway standards but has only one lane in each direction to avoid adversely impacting the Old Man of the Mountain; such a road is known as a Super-2. Around 2002, the road, which had been signed as US 3 TO I-93, was resigned as a concurrency of I-93 and US 3. Exit numbers, which had been discontinuous with I-93, were renumbered to fit the rest of I-93. Thus this gap may be no more.
  • I-95. Probably the most well known and significant of the Interstate gaps, I-95 is discontinuous near Trenton, New Jersey. Coming north from Philadelphia, Pennsylvania, I-95 loops around the north side of Trenton and ends at US 1, where it becomes I-295, which heads back south. The other section of I-95 begins on the Pennsylvania Turnpike at the Pennsylvania/New Jersey state line, and heads north along the New Jersey Turnpike. Originally I-95 was planned have left the alignment north of Trenton and headed northeast to I-287 and run east along I-287 to the Turnpike, but this "Somerset Freeway" was never built. Extensions over the years have taken I-95 several miles further north to the US 1 interchange northeast of Trenton, and south along the New Jersey Turnpike to the Pennsylvania state line. Eventually an interchange will be built connecting the southern alignment with the Pennsylvania Turnpike, and I-95 will be rerouted via it, with the part north of that interchange becoming an extension of I-295.

Freeway gaps

Undivided freeways

This section talks about Super-2s and other undivided freeway sections of the Interstate.

Drawbridges

Connection gaps

  • I-176 didn't connect directly to I-76 at Morgantown, Pennsylvania until 1996.
  • I-238 in San Francisco, in spite of being a three-digit Interstate, does not correspond to an I-38, per normal numbering rules. Indeed, I-38 does not exist, and I-238 actually intersects two spurs of I-80. I-238 was named after CA-238, because there were eight I-80 spurs in California already, and a CA-180. (California does not like to use the same number twice.)
  • I-585 used to connect with I-85 in Spartanburg, South Carolina, but I-85 was moved to a bypass and now I-585 ends at Business Loop I-85. The signed connection to I-85 is via a surface section of US 176. Additionally, some I-585 shields are present at the other end after the road has passed traffic lights, but these may be posted in error, since some signs mark the road there as Business Spur I-585.
  • I-587 in Kingston, New York connects with I-87 via a roundabout. There are no traffic lights or other cross traffic in the connection, and so it is debated whether this actually counts as a gap.
  • The following Interstates connect to their parents only via Interstates of a different parent; it is allowed for this connection to be via a same-parented Interstate (like I-280 in California being connected to I-80 via I-680).
    • I-210 in California at present does not directly connect to I-10, though it used to (via what is now CA 57) and will again by 2008 when the last segment of CA 210 is finished and renamed to I-210.
    • None of the spurs of I-78 (I-278, I-478, I-678, I-878) connects to its parent. I-78 was planned to extend through New York City and end as two branches, where I-295 and I-695 now end at I-95. I-478 comes the closest, and would have intersected if the Westway project wasn't canceled; I-278 was planned to extend northwest to I-78 at NJ 24.


Primary Interstate Highways Interstate Highway marker
4 5 8 10 12 15 16 17
19 20 22 24 25 26 27 29
30 35 37 39 40 43 44 45
49 55 57 59 64 65 66 68
69 70 71 72 73 74 75 76 (W)
76 (E) 77 78 79 80 81 82 83
84 (W) 84 (E) 85 86 (W) 86 (E) 87 88 (W) 88 (E)
89 90 91 93 94 95 96 97
99 238 H-1 H-2 H-3
Unsigned Interstate Highways
A-1 A-2 A-3 A-4 PRI-1 PRI-2 PRI-3
Lists
Two-digit Interstates - Three-digit Interstates
Gaps in Interstates - Intrastate Interstates
Interstate standards - Proposed Interstates

Sources

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