For most of its length, Interstate 93 indirectly parallels U.S. Route 3. Particularly in New Hampshire, the two highways have several interchanges with each other, as well as a concurrency through Franconia Notch State Park.
Bolded cities are officially-designated control cities for signs
Interstate 93 begins in the south at exit 12 of I-95 in Canton, Massachusetts. I-93 begins co-signed with U.S. Route 1 North. At this junction, I-95 North heads to the northwest (co-signed with U.S. Route 1 South, as well as Route 128, which begins at the interchange), to serve as the beltway around Boston, while I-95 South runs by itself southwest through Boston's southeastern suburbs towards Rhode Island.
The first few miles of I-93 run almost due east through Boston's southern suburbs, passing through Canton and Randolph. In Randolph, I-93 meets the northern end of Route 24 (Fall River Expressway/AMVETS Memorial Highway) at Exit 4. I-93 continues east into Braintree, interchanging with Route 3, the major freeway linking Boston to Cape Cod, at Exit 7 (known locally as the "Braintree Split"). Route 3 North joins I-93 and US-1, and the highway turns north towards Boston.
Upon turning northward, the highway is known as the Southeast Expressway through Quincy, Milton and Boston's Dorchester section. After the Massachusetts Avenue connector exit, the highway officially becomes the John F. Fitzgerald Expressway, which is also known as the Central Artery, and passes beneath downtown Boston. A major intersection with the Massachusetts Turnpike/Interstate 90 (Exit 20) takes place just south of downtown Boston. After the massive interchange, motorists use the Thomas P. O'Neill Jr. Tunnel to travel underneath the city and then use Zakim Bunker Hill Bridge to cross the Charles River. Two exits are located in the tunnel, where the speed limit is an hour. Route 3 leaves the Artery just before the Zakim bridge via Exit 26, and U.S. Route 1 leaves the Artery just after the bridge, via Exit 27 (no southbound access). From Boston through the rest of Massachusetts, Concord, NH appears as the control city on northbound overhead signs. The Artery ends as I-93 continues north out of the city.
I-93 continues through the northern suburbs of Boston, coming to a second intersection with Interstate 95. Travelers going north can either change over to I-95 north to eventually reach Maine, or remain on I-93 towards New Hampshire. Farther north, in Andover, I-93 meets I-495, providing access to Worcester to the southwest and New Hampshire's seacoast region to the northeast. Just south of the state line, I-93 crosses the Merrimack River into Methuen, where it interchanges with Route 213, a connector between I-93 and I-495. I-93 then crosses into New Hampshire.
In all, I-93 has 48 numbered exits in Massachusetts, although several numbers are skipped in and near Boston. Exit 48 in Methuen, just before the New Hampshire state line, is the highest-numbered exit along the entire route. Due to the highway being one of the two major Interstates that enter Boston directly (Interstate 90 is the other), nearly the entire length of the highway in Massachusetts carries four lanes in each direction. Average daily traffic volumes on I-93 in the state range from 100,000 vehicles at the New Hampshire border and 150,000 vehicles at the southern end at I-95 to over 200,000 vehicles through Braintree and Quincy.
Interstate 93 travels just over in the Granite State; around 2/3 of the highway's total distance. Serving as the main interstate route in New Hampshire, it connects nearly every major city and town in the state, including both the state capital, Concord, and its largest city, Manchester. Beyond Concord are the towns of Tilton, Plymouth, and Littleton.
Between the northern end of I-293 in Hooksett and the beginning of I-89 in Bow, I-93 also carries the northern end of the Everett Turnpike. There is one toll booth along this section, at Exit 11 in Hooksett; toll for passenger cars is currently $1 (75¢ at the ramp toll booth). This is the only toll collected along the entire length of Interstate 93. I-93 in New Hampshire is also notable for having state liquor stores serve as rest areas, which are passed just after the toll plaza, traveling north. There are separate stores on both sides of the Interstate for travelers in each direction.
I-93 enters New Hampshire at Salem, where the current reconstruction of the Exit 1 ramps (leading to the Mall at Rockingham Park) along with the reduction of the freeway from 4 northbound lanes to only 2 tends to cause traffic backups. A rest area/welcome center is available on the northbound side of the freeway, directly before Exit 1. I-93 remains only 2 lanes wide in each direction for its first , until the split with Interstate 293 and the junction with New Hampshire Route 101 add a third lane back to the freeway. I-93 and New Hampshire Route 101 run concurrently for about a mile before New Hampshire Route 101 heads directly east as its own freeway, serving Portsmouth and the Seacoast region. I-93 keeps three lanes of traffic until the junction with Interstate 89, when it reduces back to two, and remains a two-lane freeway through most of its journey northward, with the only exception being the Franconia Notch section.
It crosses the Merrimack River again before going through the state capital of Concord. In Concord, Interstate 393 heads directly east (co-signed with eastbound U.S. Route 4 and U.S. Route 202), providing another route to the Seacoast region. Westbound U.S. Route 4 joins I-93 and runs concurrently with it until Exit 17 for Penacook, about further north, before exiting westward. Continuing north, I-93 traverses the Lake Winnipesaukee tourist region and makes its way north through the heart of the White Mountains Region. I-93 passes through Franconia Notch State Park as a Super-2 parkway, the only instance of a single lane Interstate highway in the United States. This stretch carries a 45 mile per hour speed limit. For the trip through Franconia Notch, I-93 and U.S. Route 3 run concurrently.
Beyond Franconia Notch State Park, U.S. Route 3 heads northeastward through the Great North Woods region, while I-93 runs to the northwest. The final town along I-93 in New Hampshire is Littleton, served by three exits. Many motorist services are available at Exit 42. After passing through town, it crosses the Connecticut River into Vermont. The last exit along I-93 is exit 44 for Monroe, through which a rest area/welcome center is accessible to travelers on both sides of the highway.
The Southeast Expressway was constructed between 1954 and 1959, at the same time the Fitzgerald Expressway (Central Artery) was built. Its northern terminus is at Exit 18 (Massachusetts Avenue) in South Boston, a former Y-interchange where the cancelled Inner Belt (I-695) was to meet with the expressway and the Central Artery. The southern terminus is at the Y-interchange (the "Braintree Split") at Exit 7 in Braintree (where Route 128 "unofficially" begins).
A section of the Expressway, beginning south of the Savin Hill overpass and ending just before the junction with Route 3, utilizes a "zipper lane", in which a movable barrier carves out a high occupancy vehicle lane in the non-peak side of the highway during rush hour.
The Central Artery, officially the John F. Fitzgerald Expressway, was a section of highway in downtown Boston constructed in the 1950s and was originally designed as a fully elevated highway. This new highway was greatly disliked by the citizens of the city because it cut the heart of the city in half, cast long, dreary shadows and was an eyesore to the community. Because of the public outcry, Gov John Volpe ordered the southern half of the highway redesigned so that it was underground; this section became known as the Dewey Square Tunnel. With the cancellation of the highway projects leading into the city in 1972 by Gov. Francis W. Sargent, the Central Artery gained the designation of Interstate 93 in 1974. It has also carried the local highway designations of U.S. Route 1 (since 1989) and Route 3.
By the mid-1970s, I-93 had outgrown its capacity and had begun to deteriorate due a lack of maintenance. State Transportation Secretary Frederick P. Salvucci, aware of the issues surrounding the elevated roadway, proposed a plan conceived in the early 1970s by the Boston Transportation Planning Review to replace the rusting elevated six-lane Central Artery with a new, more efficient underground roadway. This plan was merged with a long-standing proposal to build a third harbor tunnel to alleviate congestion in the Sumner and Callahan tunnels to East Boston; the new plan became known as the Central Artery/Tunnel Project or the Big Dig.
These new roadways were built during a twelve-year period from 1994 to early 2006. The massive project became the largest urban construction project ever undertaken in American history. Construction on the new I-93 segment was not without serious issues: a lengthly Federal environmental review pushed the start of construction back form approximately 1990, causing many inflationary increases; funding for the project was the subject of several political battles between Pres. Ronald Reagan and Rep. Thomas P. O'Neill, Jr. Major construction on the new roadway was done while maintaining the old roadway, a step that also greatly increased the cost of the project. The original Charles River crossing, named Scheme Z, was the object to great public outcry similar to that of the building of the original highway. The outcry eventually led to the replacement of Scheme Z with a newer, more sleek cable-stayed bridge and complementing exit for Cambridge, increasing the cost even more.
In Downtown Boston, I-93 is now made up of the Thomas P. O'Neill Jr. Tunnel and the Zakim Bunker Hill Bridge, which spans the Charles River. The underground construction of the tunnel system was completed as of October, 2006; however, repairs continue to many parts of the tunnel due to water leakage because of improper construction of the slurry walls supporting the O'Neill tunnel. The former route of the above ground Artery, so named "the other Green Monster" by Mayor Thomas Menino, was replaced mostly by open space known formally as the Rose Kennedy Greenway.
Additional improvements were done in the South Bay section of the highway: The I-90/I-93 interchange was completely redesigned, a new HOV lane extending from the zipper lane in Quincy was added and the South Boston Haul road that was constructed to bypass truck traffic around residential streets in the South End is now open to general traffic.
Hazardous cargoes are now prohibited from I-93 in Boston due to safety issues in the tunnels; these cargoes must now exit at either the Leverett Circle connector in Cambridge when traveling southbound or at the Massachusetts Ave. exit when traveling northbound.
The Northern Expressway was constructed from Medford to the New Hampshire border between 1956 and 1963. It was extended through Somerville and Charlestown to the Central Artery, U.S. Route 1, and the planned route of the Inner Belt between 1965 and 1973. Because it was already under construction, the highway was granted an exception to the moratorium on highway expansion inside Route 128 which was announced in 1970.
I-93's original southern terminus was in Cambridge (just north of Boston) where it was to meet the Inner Belt (I-695). However, when that route was canceled, and the I-95 section into Boston was canceled and rerouted along Route 128 in the mid-1970s, I-93's route was extended an additional down the Central Artery (which had been signed as a concurrency of I-95/MA-3 before I-95 was rerouted) and the Southeast Expressway (what was then just Route 3) from Boston to Braintree and then west along former Route 128 to its intersection with I-95 in Canton.
In an attempt to alleviate rush-hour traffic jams, travel in the breakdown lane of I-93 is permitted on a small stretch between Exit 41 and Exit 47/48. This extra travel is permitted on the southbound side on weekdays between 6AM and 10AM, and on the northbound side between 3PM and 7PM. However, on most busy days this fails to prevent traffic delays. The Massachusetts State Police is displeased with this arrangement, citing that traffic in the breakdown lanes interferes with the ability of emergency vehicles to respond to accidents.
Originally planned to follow the alignment of US 3 through Nashua along the Everett Turnpike, this was changed before construction to the current route through Salem largely due to the intervention of the owners of Rockingham Park. Exit 1 in Salem was originally designed and built with ramps allowing northbound traffic to exit to the race track and return drivers to southbound 93 only. The complementary ramps were added much later, with the southbound off ramp being a particularly tight and dangerous turn squeezed within the curve of the southbound on ramp.
An 8 mile (13 km) section of I-93 through Franconia Notch State Park, called the Franconia Notch Parkway in New Hampshire, was constructed as a two-lane freeway with a median divider. This was built as a compromise between the state's park department and highway officials. The speed limit on the Parkway is 45 mph (70 km/h). Originally, this section's signage read "U.S. 3 TO I-93" in this area complete with its own exit number sequence, but this has since been replaced by I-93 and US-3 signage along the entire length of the Parkway. The exits were renumbered to Exit 34A, 34B, and 34C.
The plans call for The New Hampshire Department of Transportation to widen the southernmost 20 miles of I-93 to four lanes in each direction, from the current two. In addition, all five interchanges along this length will be upgraded to accommodate larger amounts of traffic, including replacing many aging bridges. Smaller construction projects at some of the interchanges are already taking place.
|Norfolk||Canton||begins concurrent with|
|0.00||, Portsmouth||The mainline of I-93 South defaults onto I-95 North. US-1 South continues concurrent with I-95 North and Route 128 North begins at this interchange.|
|0.33||1||- Providence||Southbound exit and northbound entrance|
|Milton||2.86||3||Ponkapoag Trail - Houghton's Pond|
|Randolph||3.50||4||Fall River Expressway/Amvets Highway|
|7.16||7||Route 3 enters northbound and exits southbound.|
|Quincy||8.51||8||Furnace Brook Parkway - Quincy|
|Milton||9.33||9||Bryant Avenue - West Quincy||Southbound exit and northbound entrance|
|9.33||9||Adams Street - Milton, North Quincy||Northbound exit and southbound entrance|
|9.91||10||Squantum Street - Milton||Southbound exit only|
|10.86||11A||Granite Avenue - East Milton||Southbound exit and northbound entrance|
|10.86||11B||Signed as exit 11 northbound; no northbound entrance|
|Suffolk||Boston||12||Southbound exit and northbound entrance|
|13||Freeport Street - Dorchester||Northbound exit and southbound entrance|
|14||Morrissey Boulevard - JFK Library||Northbound exit and southbound entrance|
|15||Columbia Road - Edward Everett Square, JFK Library|
|16||Southampton Street - Andrew Square||Northbound exit and southbound entrance|
|18||Frontage Road, Massachusetts Avenue - Roxbury, Andrew Square|
|20||Northbound exit and southbound entrance|
|20B||Southbound exit and northbound entrance; also a ramp from I-90 west to I-93 north|
|20A||South Station||Northbound exit is part of exit 20|
|23||Purchase Street||No northbound exit|
|24A||Government Center||Signed as exit 23 northbound|
|24B||Southbound exit and northbound entrance|
|26||, North Station||North end of Route 3 overlap||leaves|
|27||North end of US 1 overlap. northbound exit/southbound entrance only. Access to US-1 North via Exit 26 southbound.||leaves|
|29||Signed as exit 30 southbound|
|Stoneham||34||Northbound exit and southbound entrance|
|35||Winchester Highlands, Melrose||Southbound exit and northbound entrance|
|Woburn||36||Montvale Avenue - Stoneham, Woburn|
|Reading||37||Signed as exits 37A (north) and 37B (south)|
|Woburn||37C||Commerce Way, Atlantic Avenue|
|Essex||Andover||42||Dascomb Road - Tewksbury|
|43||Signed as exits 43A (east) and 43B (west) southbound|
|44||Signed as exits 44A (north) and 44B (south)|
|45||River Road - South Lawrence|
|MA-NH state line|
|Rockingham||Salem||1.76||1||Rockingham Park Boulevard to Route 28 / Route 38 - Salem|
|3.00||2||Pelham Road to Route 38 / Route 97 - Salem, Pelham|
|Windham||5.78||3||Route 111 - Windham, North Salem|
|Londonderry||11.66||4||Route 102 - Derry, Londonderry|
|15.24||5||Route 28 - North Londonderry|
|19.43||Route 101 west / I-293 - Manchester Airport, Bedford, Manchester||Route 101 joins northbound and leaves southbound.|
|20.60||6||Candia Road, Hanover Street|
|21.31||7||Route 101 east - Portsmouth, Seacoast||Route 101 leaves northbound and joins southbound.|
|22.01||8||Wellington Road / Bridge Street to Route 28A|
|Merrimack||Hooksett||23.86||9||US 3 / Route 28 - Hooksett, Manchester|
|25.65||10||Route 3A - Hooksett|
|26.31||I-293 - Manchester, Nashua||Everett Turnpike continues south on I-293.|
|28.66||11||Hackett Hill Road to Route 3A - Hooksett|
|Bow||35.37||I-89 - Lebanon, White River Junction VT|
|Concord||36.04||12||Route 3A (South Main Street) - Bow Junction||To I-89|
|37.21||13||US 3 (Manchester Street) - Downtown Concord|
|38.34||14||Route 9 (Loudon Road) - State Offices|
|38.87||15A||I-393 / US 4 / US 202 east - Loudon, Portsmouth||US 4 joins northbound and leaves southbound.|
|38.87||15B||US 202 west to US 3 (North Main Street)|
|40.29||16||NH Route 132 - East Concord|
|44.45||17||US 4 west to US 3 / Route 132 - Boscawen, Penacook||US 4 joins southbound and leaves northbound|
|Canterbury||47.72||18||West Road to Route 132 - Canterbury|
|Northfield||54.80||19||Route 132 - Northfield, Franklin||Northbound exit, southbound entrance.|
|Belknap||Tilton||56.72||20||US 3 / Route 11 / Route 132 / Route 140 - Laconia, Tilton|
|Sanbornton||60.97||22||Route 127 - Sanbornton, West Franklin|
|New Hampton||69.01||23||Route 104 / Route 132 - New Hampton, Meredith|
|Grafton||Ashland||75.06||24||US 3 / Route 25 - Ashland, Holderness|
|Holderness||79.75||25||Route 175A to Holderness Road - Plymouth|
|Plymouth||80.64||26||US 3 / Route 25 / Route 3A - Plymouth, Rumney|
|Campton||83.50||27||Blair Bridge to US 3 - West Campton|
|28||Route 49 to Route 175 - Campton, Waterville Valley|
|Thornton||88.29||29||US 3 - Thornton|
|Woodstock||94.78||30||US 3 - Woodstock, Thornton|
|97.05||31||Tripoli Road to Route 175|
|100.20||32||Route 112 - Lincoln, North Woodstock|
|Lincoln||102.23||33||US 3 - North Woodstock, North Lincoln|
|Begin Franconia Notch Parkway|
|34A||US 3 South - Flume Gorge Park Information Center||No southbound entrance.|
|Franconia||110.02||34B||Cannon Mountain Tramway - Old Man Historic Site|
|110.82||34C||Route 18 - Echo Lake Beach, Peabody Slopes, Cannon Mountain|
|End Franconia Notch Parkway|
|112.36||35||US 3 north - Twin Mountain, Lancaster||Northbound exit, southbound entrance.|
|112.91||36||Route 141 to US 3 - South Franconia, Twin Mountain|
|115.61||37||Route 18 / Route 142 - Franconia, Bethlehem||Northbound exit, southbound entrance.|
|116.39||38||Route 18 / Route 116 / Route 117 - Franconia, Sugar Hill||Also signed southbound as to Route 142|
|Bethlehem||118.95||39||Route 18 / Route 116 - North Franconia, Sugar Hill||Southbound exit, northbound entrance.|
|120.72||40||US 302 / Route 18 - Bethlehem, Twin Mountain|
|Littleton||122.28||41||Cottage Street to US 302 / Route 18 / Route 116 - Littleton, Whitefield|
|124.26||42||US 302 to Route 10 - Littleton, Woodsville|
|125.88||43||Route 135 to Route 18 - Littleton, Dalton|
|130.07||44||Route 18 / Route 135 - Monroe, Waterford VT|
|NH-VT state line|
|Caledonia||Waterford||7.51||1||Route 18 to US 2 - St. Johnsbury|
|11.10||I-91 - St. Johnsbury, White River Junction||Northbound junction only.|