List of primary Interstate Highways

From Wikipedia, the free encyclopedia

There are 71 primary Interstate Highways in the Interstate Highway System, a network of freeways in the United States. These primary highways are assigned one- or two-digit route numbers, whereas their associated auxiliary Interstate Highways receive three-digit route numbers. Typically, even-numbered Interstates run east–west, with lower numbers in the south and higher numbers in the north; odd-numbered Interstates run north–south, with lower numbers in the west and higher numbers in the east. Route numbers divisible by 5 usually represent major coast-to-coast or border-to-border routes (ex. I-10 connects Santa Monica, California to Jacksonville, Florida, extending between the Pacific and Atlantic oceans). Auxiliary highways have an added digit prefixing the number of the parent highway.

FormedJune 29, 1956[1]
InterstatesInterstate X (I-X)
Quick facts Dwight D. Eisenhower National System of Interstate and Defense Highways, System information ...
Dwight D. Eisenhower National System of Interstate and Defense Highways
Interstate 90 marker
Eisenhower Interstate System sign
Highway shield for Interstate 90 and the Eisenhower Interstate System
Primary Interstate Highways in the 48 contiguous states as of 2024
System information
FormedJune 29, 1956[1]
Highway names
InterstatesInterstate X (I-X)
System links
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Five route numbers are duplicated in the system; the corresponding highways are in different regions, reducing potential confusion. In addition to primary highways in the contiguous United States, there are signed Interstates in Hawaii and unsigned Interstates in Alaska and Puerto Rico.

Contiguous United States

There are 71 primary interstate highways in the 48 contiguous United States as well as five former and one future primary interstate highway. This number does not include auxiliary Interstate Highways.

More information Number, Length (mi) ...
Number Length (mi)[2] Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
I-2 46.8075.32 US 83/Bus. US 83-S in La Joya, TXI-69E/US 77/US 83 in Harlingen, TX 02013-01-012013current Unfinished in Texas; Texas only
I-4 132.30212.92 I-275 in Tampa, FLI-95/SR 400 at Daytona Beach, FL 01957-01-011957[3]current Florida only
I-5 1,381.292,222.97 Fed. 1/Fed. 1D at San Diego, CAHighway 99 at Blaine, WA 01957-01-011957[3]current Serves three states: California, Oregon, Washington
Associated routes: I-105, I-205, I-305, I-405, I-505, I-605, I-705, I-805; Planned: I-905 in California
I-8 350.34563.82 Sunset Cliffs Boulevard & Nimitz Boulevard in San Diego, CAI-10 in Casa Grande, AZ 01964-01-011964current Serves two states: California, Arizona
I-10 2,460.343,959.53 SR 1 in Santa Monica, CAI-95/US 17 in Jacksonville, FL 01957-01-011957current Serves eight states: California, Arizona, New Mexico, Texas, Louisiana, Mississippi, Alabama, Florida
Associated routes: I-110, I-210, I-310, I-410, I-510, I-610, I-710, I-910
I-11 54.19387.215 US 93 at the Arizona state lineFuture I-11/US 95/SR 157 in Las Vegas, NV 02017-01-012017current Unfinished in Nevada; Nevada only; planned in one more: Arizona
I-12 85.59137.74 I-10 in Baton Rouge, LAI-10/I-59 in Slidell, LA 01967-01-011967current Louisiana only
I-14 25.1040.39 US 190 & US 190 Bus. in I-35/US 190 in Belton, TXI-35/US 190 in Belton, TX 02017-01-262017current Unfinished in Texas; Texas only; planned in four more: Louisiana, Mississippi, Alabama, Georgia
Planned associated routes: I-14N, I-14S, and I-214 in Texas
I-15 1,433.522,307.03 I-8 & SR 15 in San Diego, CAHighway 4 at Sweetgrass, MT 01957-01-011957current Unfinished in California; serves six states: California, Nevada, Arizona, Utah, Idaho, Montana
Associated routes: I-115, I-215, I-315
I-16 166.81268.45 I-75/SR 540 in Macon, GAMontgomery Street in Savannah, GA 01966-01-011966current Georgia only
Associated route: I-516
I-17 145.93234.85 I-10/US 60 in Phoenix, AZI-40/SR 89A in Flagstaff, AZ 01961-01-011961current Arizona only
I-19 63.43102.08 I-19 BL in Nogales, AZI-10 in Tucson, AZ 01972-01-011972current Arizona only
Uses kilometers instead of miles
I-20 1,539.382,477.39 I-10 in Reeves County, TXI-95 & I-20 Bus. in Florence, SC 01957-01-011957current Serves six states: Texas, Louisiana, Mississippi, Alabama, Georgia, South Carolina
Associated routes: I-220, I-520, I-820
I-22 202.22325.44 I-269/US 78/MS 304 in Byhalia, MSI-65 in Birmingham, AL 02012-01-012012current Unfinished in Alabama; serves two states: Mississippi, Alabama
Planned associated routes: I-222 and I-422 in Alabama
I-24 316.36509.13 I-57 in Pulley's Mill, ILI-75/US 74 in East Ridge, TN 01962-01-011962current Serves four states: Illinois, Kentucky, Tennessee, Georgia
Associated route: I-124
I-25 1,061.671,708.59 I-10/US 85/US 180 in Las Cruces, NMI-90/US 87 in Buffalo, WY 01957-01-011957current Serves three states: New Mexico, Colorado, Wyoming
Associated route: I-225
I-26 328.09528.01 US 11W/US 23 in Kingsport, TN
I-40/I-240/US 74 in Asheville, NC		US 19/US 23 south of Forks of Ivy, NC
US 17 in Charleston, SC		 01960-01-011960current Unfinished in North Carolina; serves three states: Tennessee, North Carolina, South Carolina
Associated routes: I-126, I-526
I-27 128.332206.530 US 87 in Lubbock, TXI-40/US 60/US 87/US 287 in Amarillo, TX 01969-01-011969current Unfinished in Texas; Texas only; planned in one more: New Mexico; Planned associated routes in Texas: I-27E, I-27W, I-27N[4]
I-29 750.581,207.94 I-35/I-70/US 24/US 40/US 71 in Kansas City, MOPTH 75 at Pembina, ND 01957-01-011957current Serves four states: Missouri, Iowa, South Dakota, North Dakota
Associated routes: I-129, I-229
I-30 366.76590.24 I-20 northeast of Aledo, TXI-40/US 65/US 67/US 167/AR 107 in North Little Rock, AR 01957-01-011957current Serves two states: Texas, Arkansas
Associated routes: I-430, I-530, I-630
I-31 —— I-94 in Fargo, NDUS 81 & PTH 75 at Pembina, ND 01957-01-01195701958-01-011958 Served North Dakota only
Replaced by a northward extension of I-29
I-35 1,569.062,525.16 US 83 in Laredo, TX
I-35W & I-35E in Denton, TX
I-35W & I-35E in Columbus, MN		I-35W & I-35E in Hillsboro, TX
I-35W & I-35E in Burnsville, MN
MN 61 in Duluth, MN		 01956-01-011956current Serves six states: Texas, Oklahoma, Kansas, Missouri, Iowa, Minnesota
Associated routes: I-35E, I-35W, I-135, I-235, I-335, I-435, I-535, I-635
I-37 143.00230.14 US 181/SH 35 in Corpus Christi, TXI-35/US 281 in San Antonio, TX 01959-01-011959current Texas only
I-39 306.14492.68 I-55/US 51 in Normal, ILUS 51/WIS 29 west of Rothschild, WI 01984-01-011984current Serves two states: Illinois, Wisconsin
I-40 2,556.614,114.46 I-15 in Barstow, CAUS 117 in Wilmington, NC 01957-01-011957current Serves eight states: California, Arizona, New Mexico, Texas, Oklahoma, Arkansas, Tennessee, North Carolina
Associated routes: I-140, I-240, I-440, I-540, I-640, I-840
I-41 175.00281.64 I-94/US 41 in Russell, ILI-43/US 41/US 141 in Howard, WI 02015-01-012015current Serves two states: Illinois, Wisconsin
I-42 190310 I-35 in Noble County, OKI-49 in Springdale, AR proposed— Future Interstate; will serve two states: Oklahoma, Arkansas
I-42 31.550.7 I-40/NC 540 southeast of Garner, NC
US 70 in Goldsboro, NC		US 70/US 70 Bus. southeast of Clayton, NC
US 70 in La Grange, NC		 02024-01-012024current Unfinished in North Carolina; North Carolina only
I-43 191.55308.27 I-39/I-90 in Beloit, WII-41/US 41/US 141 in Howard, WI 01981-01-011981current Wisconsin only
I-44 636.691,024.65 US 82/US 277/US 281/US 287 in Wichita Falls, TXI-70 in St. Louis, MO 01957-01-011957current Serves three states: Texas, Oklahoma, Missouri
Associated routes: I-244, I-344, I-444
I-45 284.91458.52 SH 87/Spur 342 in Galveston, TXI-30/I-345/US 67 in Dallas, TX 01971-01-011971current Texas only
Associated route: I-345
I-49 547.52881.15 I-10/US 167/LA 182 in Lafayette, LA
I-220 in Shreveport, LA
I-40/US 71 at Alma, AR		I-20 in Shreveport, LA
US 59/US 71 in Texarkana, AR
I-435/I-470/US 50/US 71 in Kansas City, MO		 01984-01-011984current Unfinished in Arkansas and Louisiana; serves three states: Louisiana, Arkansas, Missouri; planned in one more: Texas
I-55 964.251,551.81 I-10 in LaPlace, LAUS 41 in Chicago, IL 01960-01-011960current Serves six states: Louisiana, Mississippi, Tennessee, Arkansas, Missouri, Illinois
Associated routes: I-155, I-255, I-355, I-555
I-57 508.92819.03 I-40/US 67/US 167 in North Little Rock, AR
I-55/US 60 in Sikeston, MO		US 67/US 412/US 412B in Walnut Ridge, AR
I-94 in Chicago, IL		 01965-01-011965current Unfinished in Missouri and Arkansas; serves three states: Arkansas, Missouri, Illinois.
I-59 445.23716.53 I-10/I-12 in Slidell, LAI-24 in Wildwood, GA 01960-01-011960current Serves four states: Louisiana, Mississippi, Alabama, Georgia
Associated routes: I-359, I-459, I-759
I-64 963.521,550.64 I-70/US 40/US 61 in Wentzville, MOI-264/I-664/US 13/US 58/US 460 in Chesapeake, VA 01961-01-011961current Serves six states: Missouri, Illinois, Indiana, Kentucky, West Virginia, Virginia
Associated routes: I-264, I-464, I-564, I-664
I-65 887.301,427.97 I-10 in Mobile, ALUS 12/US 20 in Gary, IN 01958-01-011958current Serves four states: Alabama, Tennessee, Kentucky, Indiana
Associated routes: I-165, I-265, I-465, I-565, I-865; Planned: I-365 in Kentucky
I-66 —— Wichita, KSNear Pikeville, KY 01991-01-01199102015-01-012015[5] Served four states: Kansas, Missouri, Illinois, Kentucky
Associated routes: I-66 Spur in Kentucky
The project was unpopular and ultimately cancelled without the interstate being completed; I-66 Spur eventually became I-165
I-66 76.28122.76 I-81 southwest of Middletown, VAUS 29 in Washington, DC 01961-01-011961current Serves DC and one state: Virginia
I-68 113.15182.10 I-79 in Morgantown, WVI-70/US 40/US 522 in Hancock, MD 01991-01-011991current Serves two states: West Virginia, Maryland
I-69 910.101,464.66 US 59 in Rosenberg, TX
MS 713 southwest of Banks, MS
US 51 in Fulton, KY
US 41 in Evansville, IN		US 59 in Splendora, TX
US 51 in Memphis, TN
US 41 in Henderson, KY
Hwy 402 at Port Huron, MI		 01957-01-011957current
I-70 2,171.713,495.03 I-15 in Cove Fort, UTI-695 in Woodlawn, MD 01956-01-011956current Serves 10 states: Utah, Colorado, Kansas, Missouri, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, Maryland
Associated routes: I-170, I-270, I-370, I-470, I-670
I-71 345.57556.14 I-64/I-65 in Louisville, KYI-90 & I-490 in Cleveland, OH 01959-01-011959current Serves two states: Kentucky, Ohio
Associated routes: I-271, I-471
I-72 179.29288.54 US 36/US 36 Bus./US 61 (Avenue of the Saints)/Route 110 (CKC) in Hannibal, MOUniversity Avenue & Church Street in Champaign, IL 01970-01-011970current Serves two states: Missouri, Illinois
Associated route: I-172
I-73 101.10162.70 I‑74/US 74/US 74 Bus. west of Rockingham, NCUS 220/NC 68 northeast of Stokesdale, NC 01997-01-011997current Unfinished in North Carolina; North Carolina only; planned in five more: South Carolina, Virginia, West Virginia, Ohio, Michigan
I-74 541.62871.65 I-80 in Davenport, IA
I-77 at the Virginia state line northwest of Pine Ridge, NC
I-40 in Winston-Salem, NC
US 74 Alt./US 74 Bus. in Maxton, NC		I-75/US 52 in Cincinnati, OH
US 52 in Mount Airy, NC
US 74 Bus. northwest of Hamlet, NC
US 74 southwest of Lumberton, NC		 01974-01-011974current Unfinished in Ohio and North Carolina; serves five states: Iowa, Illinois, Indiana, Ohio, North Carolina; planned in three more: West Virginia, Virginia, South Carolina
Associated routes: I-474; Planned: I-274 in North Carolina
I-75 1,786.472,875.04 SR 826/SR 924 in Miami Lakes, FLInternational Bridge at Sault Ste. Marie, MI 01958-01-011958current Serves six states: Florida, Georgia, Tennessee, Kentucky, Ohio, Michigan
Associated routes: I-175, I-275, I-375, I-475, I-575, I-675
I-76 187.29301.41 I-70 in Arvada, COI-80 at Big Springs, NE 01975-01-011975current Serves two states: Colorado, Nebraska
I-76 435.66701.13 I-71/US 224 in Westfield Township, OHI-295/Route 42 in Bellmawr, NJ 01964-01-011964current Serves three states: Ohio, Pennsylvania, New Jersey
Associated routes: I-176, I-276, I-376, I-476, I-676
I-77 610.10981.86 I-26 in Cayce, SCI-90 in Cleveland, OH 01958-01-011958current Serves five states: South Carolina, North Carolina, Virginia, West Virginia, Ohio
Associated route: I-277
I-78 146.28235.41 I-81 in Union Township, PACanal Street in New York, NY 01957-01-011957current Serves three states: Pennsylvania, New Jersey, New York
Associated routes: I-278, I-478, I-678, I-878
I-79 343.46552.75 I-77 in Charleston, WVPA 5/PA 290/Bayfront Parkway in Erie, PA 01967-01-011967current Serves two states: West Virginia, Pennsylvania
Associated routes: I-279, I-579
I-80 2,900.764,668.32 US 101 in San Francisco, CAI-95 in Teaneck, NJ 01956-01-011956current Serves 11 states: California, Nevada, Utah, Wyoming, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, New Jersey
Associated routes: I-180, I-238, I-280, I-380, I-480, I-580, I-680, I-780, I-880, I-980
I-81 855.021,376.02 I-40 in Dandrige, TNHwy 137 at Wellesley Island, NY 01961-01-011961current Serves six states: Tennessee, Virginia, West Virginia, Maryland, Pennsylvania, New York
Associated routes: I-381, I-481, I-581, I-781
I-82 143.58231.07 I-90/US 97 in Ellensburg, WAI-84/US 30 in Hermiston, OR 01957-01-011957current Serves two states: Washington, Oregon
Associated route: I-182
I-82 —— I-81/I-84/US 6 in Scranton, PAI-95 in Teaneck, NJ 01957-01-01195701958-01-011958 Served two states: Pennsylvania, New Jersey
Was the initial designation to what is now I-380 and I-80
I-82 —— I-84 in East Hartford, CTProvidence, RI 01956-01-01195601968-01-011968 Served one state: Connecticut, was planned for one state: Rhode Island
Redesignated as I-84 in 1968
I-83 85.03136.84 President Street & Fayette Street in Baltimore, MDI-81/US 322 north of Progress, PA 01959-01-011959current Serves two states: Maryland, Pennsylvania
Associated route: I-283
I-84 769.621,238.58 I-5/US 30 in Portland, ORI-80/US 189 in Echo, UT 01980-01-011980current Serves three states: Oregon, Idaho, Utah
Associated route: I-184
I-84 232.71374.51 I-81/I-380/US 6 in Dunmore, PAI-90/Massachusetts Turnpike in Sturbridge, MA 01963-01-011963current Serves four states: Pennsylvania, New York, Connecticut, Massachusetts
Associated routes: I-384, I-684
I-85 666.051,071.90 I-65/US 82 in Montgomery, ALI-95/US 460 in Petersburg, VA 01958-01-011958current Unfinished in Alabama; serves five states: Alabama, Georgia, South Carolina, North Carolina, Virginia
Associated routes: I-185, I-285, I-385, I-485, I-585, I-785, I-885, I-985; Future/Planned: I-685 in both Alabama and North Carolina
I-86 62.85101.15 I-84/US 30 northeast of Declo, IDI-15 in Chubbuck, ID 01980-01-011980current Idaho only
I-86 254.02408.81 I-90 in Greenfield Township, PA
I-81/NY 17/NY 990G in Kirkwood, NY		NY 17/NY 26 in Vestal, NY
NY 17/NY 79 in Windsor, NY		 01999-01-011999current Unfinished in New York; serves two states: Pennsylvania, New York
I-86 38.9762.72 I-84 in East Hartford, CTI-90 in Sturbridge, MA 01968-01-01196801984-01-011984 Served two states: Connecticut, Massachusetts
Redesignated as I-84 in 1984 when the I-84 Hartford-Providence corridor was cancelled
I-87 12.9020.76 I-40/I-440/US 64 in Raleigh, NCUS 64/US 264 in Wendell, NC 02017-01-012017current Unfinished in North Carolina; North Carolina only; planned in one more: Virginia
Associated route: I-587
I-87 333.49536.70 I-278 in Port Morris, NYA-15 at Champlain, NY 01957-01-011957current New York only
Associated routes: I-287, I-587, I-787
I-88 140.60226.27 I-80/IL 5/IL 92/Route 110 (CKC) northeast of East Moline, ILI-290/Route 110 (CKC) in Hillside, IL 01987-01-011987current Illinois only
I-88 117.75189.50 I-81 in Chenango, NYI-90/New York State Thruway in Rotterdam, NY 01968-01-011968current New York only
I-89 191.12307.58 I-93/Everett Turnpike/NH 3A in Bow, NHRoute 133 at Highgate, VT 01960-01-011960current Serves two states: New Hampshire, Vermont
Associated route: I-189
I-90 3,099.744,988.55 SR 519 in Seattle, WARoute 1A in Boston, MA 01956-01-011956current Serves 13 states: Washington, Idaho, Montana, Wyoming, South Dakota, Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, New York, Massachusetts
Associated routes: I-190, I-290, I-390, I-490, I-590, I-690, I-790, I-890, I-990
Longest Interstate highway
I-91 290.37467.31 I-95 in New Haven, CTA-55 at Derby Line, VT 01958-01-011958current Serves three states: Connecticut, Massachusetts, Vermont
Associated routes: I-291, I-391, I-691
I-93 189.95305.69 I-95/US 1/Route 128 in Canton, MAI-91 in Waterford, VT 01957-01-011957current Serves three states: Massachusetts, New Hampshire, Vermont
Associated routes: I-293, I-393
I-94 1,555.432,503.22 I-90/US 87/US 212 in Lockwood, MTHighway 402 at Port Huron, MI 01956-01-011956current Serves seven states: Montana, North Dakota, Minnesota, Wisconsin, Illinois, Indiana, Michigan
Associated routes: I-194, I-294, I-394, I-494, I-694, I-794, I-894
I-95 1,905.963,067.35 US 1 in Miami, FLRoute 95 at Houlton, ME 01957-01-011957current Serves DC and 15 states: Florida, Georgia, South Carolina, North Carolina, Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, Maine
Associated routes: I-195, I-295, I-395, I-495, I-595, I-695, I-795, I-895
Longest primary north-south Interstate highway
I-96 192.032309.046 US 31 in Norton Shores, MII-75 in Detroit, MI 01959-01-011959current Michigan only
Associated routes: I-196, I-296, I-496, I-696
I-97 17.6228.36 US 50/US 301 in Parole, MDI-695/I-895A in Brooklyn Park, MD 01987-01-011987current Maryland only
I-99 161.68260.20 US 220/US 220 Bus. north of Bedford, PA
I-180/US 15/US 220 in Williamsport, PA		US 220/PA 26 northeast of Bellefonte, PA
I-86/US 15/NY 17/NY 352 at Painted Post, NY		 01998-01-011998current Unfinished in Pennsylvania; serves two states: Pennsylvania, New York
  •       Former
  •       Proposed and unbuilt
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Other regions

In addition to the 48 contiguous states, Interstate Highways are found in Hawaii, Alaska, and Puerto Rico. The Federal Highway Administration funds four routes in Alaska and three routes in Puerto Rico under the same program as the rest of the Interstate Highway System. However, these routes are not required to meet the same standards as the mainland routes:

Highways on the Interstate System in Alaska and Puerto Rico shall be designed in accordance with such geometric and construction standards as are adequate for current and probable future traffic demands and the needs of the locality of the highway.[6]

Hawaii

Map of Hawaii's Interstate Highways (excluding H-201)

The Interstate Highways on the island of Oʻahu, Hawaii are signed with the standard Interstate Highway shield, with the letter "H-" prefixed before the number. They are fully controlled-access routes built to the same standards as the mainland Interstate Highways.

More information Number, Length (mi) ...
Number Length (mi)[2] Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
H-1 27.1643.71 Route 93 in KapoleiRoute 72 in Honolulu 01960-01-011960current Associated route: H-201
H-2 8.3313.41 H-1 in Pearl CityRoute 99 in Wahiawa 01960-01-011960current
H-3 15.3224.66 H-1/H-201 in HalawaMarine Corps Base Hawaii 01997-01-011997current
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Alaska

Main article: List of Interstate Highways in Alaska
Map of Alaska's Interstate Highways

Alaska's Interstate Highways are unsigned as such, although they all have state highway numbers that do not match the Interstate Highway numbers.[7]

More information Number, Length (mi) ...
Number Length (mi)[2] Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
A-1 408.23656.98 AnchorageHwy. 1 at Alcan Border 01976-01-011976current Glenn Highway, Richardson Highway, Tok Cut-Off, Alaska Highway[8][9][10][11]
A-2 202.18325.38 TokFairbanks 01976-01-011976current Alaska Highway, Richardson Highway[9][10][11]
A-3 148.12238.38 AnchorageSoldotna 01976-01-011976current Seward Highway, Sterling Highway[8][10][11]
A-4 323.69520.93 Gateway, near PalmerFairbanks 01976-01-011976current Parks Highway[8][9][10][11]
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Puerto Rico

Main article: List of highways in Puerto Rico § Interstates
Map of the Interstates in Puerto Rico

Puerto Rico signs its Interstate Highways as territorial routes, as the numbers do not match their official Interstate Highway designations. Many of the territory's routes are freeway-standard toll roads.[12]

More information Number, Length (mi) ...
Number Length (mi)[2] Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
PR-1 71.08114.39 PR-2 in PoncePR-2 in San Juan 01976-01-011976current Follows PR-52
PR-2 138.13222.30 PR-1 in PoncePR-3 in San Juan 01976-01-011976current Follows PR-22
PR-3 40.5665.27 PR-3 in HumacaoPR-2 in San Juan 01976-01-011976current Follows PR-66
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See also

References

External links

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