Louisiana Highway 643 is a state highway

State highway

State highway, state road or state route can refer to one of three related concepts, two of them related to a state or provincial government in a country that is divided into states or provinces :#A...

 in Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

 which serves St. James and St. John the Baptist Parishes

St. John the Baptist Parish, Louisiana

St. John the Baptist Parish is a parish located in the U.S. state of Louisiana.The parish seat is Edgard, an unincorporated area and the unofficial parish captial is LaPlace, an unincorporated area. St. John the Baptist is one of the original 19 parishes in Louisiana. In 2010, its population was...

. It spans 6.05 miles (9.7 km) in a west to east direction.

Route description

LA 643 runs eastward from an intersection with LA 20

Louisiana Highway 20

Louisiana Highway 20 is a state highway that serves Terrebonne Parish, Lafourche Parish, and St. James Parish. It spans a total of as a two lane, undivided road.-Route description:...

 in Vacherie. After little more than a mile, it turns southward at an intersection with LA 644

Louisiana Highway 644

Louisiana Highway 644 is a state highway in Louisiana which serves St. James Parish. It spans in a west to east direction and is known locally as N. Spruce Street.-Route description:...

(N. Spruce Street). After less than a mile, the highway again turns eastward. It ends at a small community on the western shore of Lac des Allemands

Lac des allemands

Lac des Allemands is a lake located mostly in St. John the Baptist Parish and partly in Lafourche and St. Charles Parishes. It is west of New Orleans and is connected to Lake Salvador by the Bayou des Allemands...

.

It is an undivided, two-lane highway for its entirety.

Junction list

Parish	Location	Mile	Junction	Notes
St. James	Vacherie Vacherie, Louisiana Vacherie is a small unincorporated community in St. James Parish, Louisiana, United States. Near the community is the WCKW/KSTE-Tower, a guyed mast noted as one of the tallest constructions on Earth.-Census-designated places:...	Western terminus of LA 643
		0.00	LA 20 Louisiana Highway 20 Louisiana Highway 20 is a state highway that serves Terrebonne Parish, Lafourche Parish, and St. James Parish. It spans a total of as a two lane, undivided road.-Route description:...
		1.5	LA 644 Louisiana Highway 644 Louisiana Highway 644 is a state highway in Louisiana which serves St. James Parish. It spans in a west to east direction and is known locally as N. Spruce Street.-Route description:...  (N. Spruce Street)	Eastern terminus of LA 644
St. John the Baptist St. John the Baptist Parish, Louisiana St. John the Baptist Parish is a parish located in the U.S. state of Louisiana.The parish seat is Edgard, an unincorporated area and the unofficial parish captial is LaPlace, an unincorporated area. St. John the Baptist is one of the original 19 parishes in Louisiana. In 2010, its population was...		6.05	End of State Maintenance at Rue St. Martin/Lac des Allemands Lac des allemands Lac des Allemands is a lake located mostly in St. John the Baptist Parish and partly in Lafourche and St. Charles Parishes. It is west of New Orleans and is connected to Lake Salvador by the Bayou des Allemands...
		Eastern terminus of LA 643