The police juries may pave, plank, gravel, macadamize, or otherwise improve the streets and alleys or any part thereof not less than one block in length, and the sidewalks, or any part thereof, and construct curbing in areas outside of municipalities and may levy and collect special taxes or local assessments on all real estate abutting the streets, alleys, sidewalks, or curbing to be improved or constructed for the purpose of defraying the costs of the improvement, either in whole or in part, as hereinafter provided.