Ridgecrest is a small town in Concordia Parish, Louisiana, United States. The population was 694 at the 2010 census. Ridgecrest is located in northeastern Concordia Parish. U.S. Routes 84 and 425 form the northeast boundary of the town; the highways lead northwest 3 miles to Ferriday and southeast 6 miles to Vidalia on the Mississippi River; Na…Ridgecrest is a small town in Concordia Parish, Louisiana, United States. The population was 694 at the 2010 census. Ridgecrest is located in northeastern Concordia Parish. U.S. Routes 84 and 425 form the northeast boundary of the town; the highways lead northwest 3 miles to Ferriday and southeast 6 miles to Vidalia on the Mississippi River; Natchez, Mississippi, is 9 miles to the southeast. The Mississippi state line is less than a mile northeast of Ridgecrest in a former channel of the Mississippi River known as Marengo Bend.