Interstate 10 (abbreviated I-10) is the southernmost east-west, coast-to-coast interstate highway in the United States. It stretches from the Pacific Ocean at State Route 1 (Pacific Coast Highway) in Santa Monica, California (map) to Interstate 95 in Jacksonville, Florida (map).

Route description
See also: Interstate 10 in California
Between its west terminus in Santa Monica, California and the East Los Angeles Interchange it is known as the Santa Monica Freeway. The Santa Monica Freeway is also called the "Rosa Parks Freeway" for the segment beginning at the San Diego Freeway (The 405 Freeway) and ending at the Harbor Freeway (The 110 Freeway), however either name can be used when referring to this stretch of road. The segment between the East Los Angeles Interchange and the city of San Bernardino, California (53 miles, or 92 km long) is known as the San Bernardino Freeway. Other names exist for the freeway. For example, a sign near the western terminus of the highway announces it as the "Christopher Columbus Transcontinental Highway". It is known to a considerably lesser degree as the "Veterans Memorial Highway" and is listed as a Blue Star Highway. Many times, Angelinos refer to it as "the 10."
A stretch in Palm Springs is signed as the "Sonny Bono Memorial Freeway" as a tribute to the late entertainer who served both as mayor and as a United States Congressman. A second stretch a short distance east in Indio is signed as the "Doctor June McCarroll Memorial Freeway". As a nurse with the Southern Pacific Railroad in 1924, Dr. McCarroll was alarmed at the number of head-on traffic collisions on a nearby stretch of then-new U.S. Route 99, today known as State Route 86. She is credited with painting a white stripe down the middle of 99 near Coachella in order to separate the two lanes of traffic. California Law Defining Highway:
The law defining the California part of Interstate 8 is California Streets & Highways Code § 310.

California
See also: Interstate 10 in Arizona
In Arizona, the highway is designated the "Pearl Harbor Memorial Highway". The portion through Phoenix is named the "Papago Freeway". This designation starts at the initial junction/southern terminus of I-17 and runs westward out to AZ Loop 101, a loop route whose current western terminus is Interstate 10. Phoenicians more often than not refer to the freeway as "the I-10"(pronounced : the eye-ten).
From the southern terminus of Interstate 17 to the junction with the AZ Loop 202 freeway, the freeway is signed as the "Maricopa Freeway". This name holds true as well for I-17 from its southern terminus to its second junction with I-10, north of McDowell Road. From Loop 202 south to Interstate 8 (eastern terminus in Casa Grande), the freeway is signed as the "Pearl Harbor Memorial Highway". ADOT also has maps that show it as the Maricopa Freeway, while AAA and other sources show it as the Pima Freeway. The latter's name is used on a stretch of Loop 101 from U.S. 60 to Interstate 17.
In Tucson, I-10 is called the Casa Grande Highway from the western edge of town to the eastern terminus of Business Loop 10, where it picks up the name, Tucson-Benson Highway from that route.
In Tucson, Arizona, between I-10 mileposts 259 and 260 are interchange ramps connecting I-10 with the northern terminus of Interstate 19 at its km post 100. I-19 leads 100 km south to its termination at the US-Mexico border at Nogales, Arizona (km post 0). Note that distance measurements on Interstate 19 are signed in metric units.
There is also a plan to widen the existing freeway in Tempe from 14 to 24 Lanes (source: [1])
Plans are under way to widen I-10 from Marana north to the I-8 interchange at Casa Grande from 4 lanes to 6 lanes starting in the later half of 2007 and continuing into 2008 and 2009.

Santa Monica, California
Los Angeles, California
San Bernardino, California
Riverside, California
Indio, California
Blythe, California
Phoenix, Arizona
Tucson, Arizona
Lordsburg, New Mexico
Deming, New Mexico
Las Cruces, New Mexico
El Paso, Texas
Van Horn, Texas
San Antonio, Texas
Houston, Texas
Beaumont, Texas
Lake Charles, Louisiana
Lafayette, Louisiana
Baton Rouge, Louisiana
New Orleans, Louisiana
Slidell, Louisiana
Bay St. Louis, Mississippi
Gulfport, Mississippi
Biloxi, Mississippi
Pascagoula, Mississippi
Mobile, Alabama
Pensacola, Florida
Tallahassee, Florida
Lake City, Florida
Jacksonville, Florida Arizona
See also: Interstate 10 in New Mexico
Interstate 10 in New Mexico follows the former path of U.S. Route 80 across the state. Only three cities of significant size are located on the interstate: Lordsburg, Deming, and Las Cruces.
At Lordsburg is the western junction of U.S. Route 70 and a concurrency and the two highways are joined all the way to Las Cruces. Several exits between Lordsburg and Deming are either for former towns (including Separ, Quincy, and Gage) or lack any town at all.
At Deming is the western junction of U.S. Route 180, which also forms a concurrency with I-10 all the way to El Paso. One mile north of Deming on US 180 is New Mexico Route 26 which serves as a short cut to north I-25 and Albuquerque.
I-10/US 70/US 180 continue east to Las Cruces which is the southern end of Interstate 25. Also, US 70 leaves Interstate 10, heading northeast to Alamogordo. Interstate 10 then turns south to the Texas state line.

New Mexico
See also: Interstate 10 in Texas
In Texas, the speed limit along I-10 from Kerr County to El Paso County is 80 mph (130 km/h), the highest in the nation. However, the night speed limit remains 65 mph (106 km/h).
From the state line with New Mexico to Texas State Highway 20 in west El Paso, I-10 is bordered by frontage roads Desert South for lanes along I-10 East (actually headed south) and Desert North for lanes along I-10 West (headed north). The interstate then has no frontage roads for nine miles but regains them east of downtown and retains them to Clint. In this stretch, the frontage roads are Gateway East for the Eastbound lanes and Gateway West for the Westbound lanes. All four frontage roads are one way streets.
A small portion of I-10 from Loop 1604 to downtown in San Antonio, Texas is known as the Northwest Expressway or the McDermott Freeway, while another portion from downtown to Loop 1604 East is called East Expressway or Jose Lopez Freeway.
In Houston, from the western suburb of Katy to downtown, I-10 is known as the "Katy Freeway." This section is currently being widened to as much as 26 lanes (12 mainlanes, 4 lanes of access roads, and 4-6 mid-freeway HOT/HOV lanes, not counting access road turning lanes) and will be one of the widest freeways in the world. The section east of downtown Houston is officially known as the "East Freeway," although it is widely known by locals as the "Baytown East Freeway" due to a marketing push by Baytown, the easternmost principal city of the Greater Houston Area.
In Beaumont, it is designated Eastex Freeway between both splits with U.S. Highway 69. Eastex is not to be confused with the designation for U.S. Highway 59 in Houston.

Texas
See also: Interstate 10 in Louisiana
In Louisiana, an 18.2-mile (29.3 km) stretch of elevated highway between Lafayette and Baton Rouge is known as the Atchafalaya Swamp Freeway, as it goes over the Atchafalaya River and the adjacent swamps. In New Orleans, a stretch of I-10 from the I-10/I-610 split near the Orleans-Jefferson parish line to the U.S. Route 90 / U.S. Route 90 Business interchange is known as the Pontchartrain Expressway. A dip near the 10-610 interchange to go underneath a railroad track is one of the lowest points in New Orleans, and is highly susceptible to flooding. Pictures of water dozens of feet deep during Hurricane Katrina are commonplace. Near Slidell, the final stretch of I-10 through the Mississippi state line is known as the "Stephen Ambrose Memorial Highway".
Most through traffic between Baton Rouge and Slidell uses Interstate 12 to bypass Interstate 10's long southward jog through New Orleans.

Mississippi
See also: Interstate 10 in Alabama
I-10 crosses from Jackson County, Mississippi and goes through Mobile County in Southwest Alabama. In Mobile, the highway is the southern terminus for Interstate 65. In downtown Mobile, I-10 goes through one of few road tunnels in Alabama, the George C. Wallace Tunnel under the Mobile River. The eastbound approach is posted at 40 mph (60 km/h) because of the sharp curve approaching the tunnel. The highway then crosses approximately eight miles of the upper part of Mobile Bay on a bridge locals refer to as the Bayway. On the other side of Mobile Bay, the highway goes through suburban Baldwin County before crossing the Perdido River into Florida.

Alabama
See also: Interstate 10 in Florida
Most of Interstate 10 in Florida travels through some of least-populated areas in the state, much of which is forested. Consequently, I-10 west of Interstate 295 in Jacksonville has only 4 lanes.

Florida
In September 2004, Hurricane Ivan's storm surge pushed up and washed out part of I-10 at the causeway over Escambia Bay near Pensacola, Florida. Westbound lanes had only a couple of sections missing, while eastbound lanes were almost completely gone for a quarter-mile (400m) section.

History
In Phoenix, a bill has been created that if passed states that the stretch of I-10 between Downtown and the suburb of Buckeye, Arizona will be widened to 24 lanes due to severe traffic problems that take place on the freeway during rush hours. This would make this stretch of the I-10 the widest along its entire length, as well as the widest highway in North America; currently, the 22-lane section of Highway 401 between Highways 403/410 and Highway 427 in Mississauga, Ontario, just east of Toronto is the widest.

Future
I-310 and I-510 are parts of what was slated to be I-410 and act as a southern bypass of New Orleans, Louisiana. I-610 is a shortcut from the eastern to western portion of New Orleans avoiding the I-10's detour into New Orleans' Central Business District.
In the aftermath of Hurricane Katrina, the I-10 Twin Span Bridge, a portion of I-10 between New Orleans and Slidell spanning the eastern end of Lake Pontchartrain, was severely damaged, causing a break in I-10 at that point. Unlike the Escambia Bay Bridge (east of Pensacola, Florida and damaged by Hurricane Ivan) which is a major artery, Interstate 12 is available to bypass New Orleans and taking I-12 to the Lake Ponchartrain Causeway allowed entry and exit to and from the Greater New Orleans area from the East. On October 14, 2005 at 3:00 PM, the eastbound span was reopened to two way traffic. On January 6, 2006 at 6:00 AM, both lanes of the westbound span were reopened to traffic using temporary metal trusses and road panels to replace damaged sections. [2] This restored all four lanes of the I-10 twin spans for normal traffic with a 45 mph (70 km/h) speed limit for the westbound lanes and 60 mph (100 km/h) for the eastbound lanes. Oversized and overweight traffic is prohibited until a new permanent six lane span is built to replace the two temporarily repaired spans. Construction is slated to begin in mid-July 2006, with the new westbound span opening in 2008/2009 and the new eastbound span opening in 2011. See WWL-TV story
In Mississippi, the twin spans crossing the Pascagoula River were opened on October 1 and are now operational, making that state's portion fully functional.
I-610 is also the designation for the "loop" circling Houston, Texas.
I-410 is also the designation for the "loop" circling San Antonio, Texas.

Alternate routes

Interstate 405 in West Los Angeles, California
Interstate 110 southwest of Downtown Los Angeles, California
Interstate 5 at the East Los Angeles Interchange in Los Angeles, California
Interstate 710 in East Los Angeles, California
Interstate 605 in El Monte/Baldwin Park, California
Interstate 15 in Ontario, California
Interstate 215 in San Bernardino, California
Interstate 17 in Phoenix, Arizona
Interstate 8 in Casa Grande, Arizona
Interstate 19 in Tucson, Arizona
Interstate 25 in Las Cruces, New Mexico
Interstate 20 near Kent, Texas
Interstate 410 in San Antonio, Texas (twice)
Interstate 35 and Interstate 37 in San Antonio, Texas
Interstate 45 in Houston, Texas
Interstate 610 in Houston, Texas (twice)
Interstate 210 in Lake Charles, Louisiana (twice)
Interstate 49 in Lafayette, Louisiana
Interstate 110 and Interstate 12 in Baton Rouge, Louisiana
Interstate 55 in La Place, Louisiana
Interstate 310 near Kenner, Louisiana
Interstate 610 (twice) and Interstate 510 in New Orleans, Louisiana
Interstate 12 and Interstate 59 in Slidell, Louisiana
Interstate 110 in Biloxi, Mississippi
Interstate 65 in Mobile, Alabama
Interstate 110 in Pensacola, Florida
Interstate 75 in Lake City, Florida
Interstate 295 and Interstate 95 in Jacksonville, Florida Auxiliary routes
The section could be improved by integrating relevant items into the main text and removing inappropriate items.

Just east of the I-10/I-510 interchange in New Orleans, there are three large similar interchanges that are not clover-leaf design. Of these three interchanges, the easternmost two are unsigned and appear to go nowhere. The westernmost interchange connects Michoud Blvd. (Louisiana State Highway 68) with I-10. The middle interchange is the former Discovery Boulevard interchange and is permanently closed, completely barricaded at the ramps and overrun by vegetation. The easternmost interchange provides access to the Bayou Sauvage National Wildlife Refuge and access to a bike path along the Lake Pontchartrain levee. (Online maps refer to this isolated dirt road as Louisiana State Highway 55. Although State Highway 55 exists more than 70 miles away in Terrebonne Parish, it does not connect to the dirt road as a terminus.) [3]
Interstate 10 is one of only three interstate highways in America that has an alternate route that's shorter than the actual route. I-12 in Louisiana provides a shortcut for I-10 travelers. U.S. 290 from Houston through Austin and back to I-10 near the village of Segovia, TX, is actually shorter than if one actually stayed on I-10 throughout Texas. (Others include Interstate 64 between Lewisburg, West Virginia and Charleston, West Virginia, where U.S. Highway 60 provides a shorter distance route between the 2 points, and Interstate 295 in Maine, which is shorter than I-95 by 8 miles between Scarborough and West Gardiner.)
In January 1994, the I-10 overpasses over La Cienega and Venice Boulevards in Los Angeles, California collapsed during the Northridge earthquake. This section of freeway bears one of the heaviest traffic loads in California, and was reopened just 66 days later after emergency around-the-clock construction.
The interstate's route through Phoenix was hotly contested in the 1960s and 1970s. A plan proposed by the Arizona Department of Transportation involved city block-sized 270-degree "helicoils" that would connect motorists to freeway lanes 100 feet (30 m) in the air, but voters killed it in 1973 as a result of opposition from the Arizona Republic and a growing nationwide anti-freeway sentiment. Ten years later, ADOT unveiled the current below grade plans. Despite local opposition, Interstate 10 was finally completed on August 10, 1990.
I-10 is one of the very few interstates that have at-grade intersections (roads that intersect it at a 90 degree angle, as opposed to an overpass with on and off ramps). These are private access roads (mostly from large ranches) which occur over a limited stretch in western Texas.
I-10 is one of only a few interstates that have 7% downhill grades in certain areas. (7% grades violate the 6% gradient maximum that's permitted on Interstates and Freeways in America.) These 7% downhill grades, according to the signs on the freeway, all occur in Kerr County in the state of Texas. Other locations on the Interstates where 7% downhill grades occur include I-70 in Colorado, I-64 in West Virginia, I-68 in West Virginia, and I-26 south of Asheville, North Carolina.
At just under 879 miles (1,414 km), the length of Interstate 10 crossing Texas, maintained by the Texas Department of Transportation, is the longest continuous untolled freeway under a single authority in North America, a title formerly held by Ontario's Highway 401. Mile marker 880 (and the corresponding exit number) near Orange, Texas are the highest numbered mile marker and exit on the interstate highway system, or for that matter, on any freeway in North America.
Interstate 10 grants through travelers a closer view of life in another country than any interstate highway in America. The dense shantytowns in Ciudad Juárez in the Mexican state of Chihuahua in some places are only about 800 ft (240 m) from I-10 and can be viewed by I-10 travelers west of Downtown El Paso, Texas.[4][5]
Texas alone contains more than a third of the interstate's entire length. El Paso, Texas (on the Texas-New Mexico border) is 785 miles (1,263 km) from the western terminus of Interstate 10, making it closer to Los Angeles than it is to Orange, Texas, approximately 880 miles (1,416 km) away. Likewise, Orange, Texas on the Texas-Louisiana border is only 789 miles (1,270 km) from the eastern terminus of Interstate 10 in Jacksonville, Florida.