The Florida Department of Transportation is constructing I-75 across the SR-84 (Alligator Alley) alignment in south Florida. This alignment crosses approximately 40 mi of habitat of the only known population of the endangered Florida panther. Panther movement and behavior are being monitored by radio tracking. Radio-collared panthers have been crossing the alignment, providing information on locations of crossings and habitat type being used. This information was used to develop measures to provide safe crossings of I-75 for the panther. Measures taken include creation of 23 wildlife crossings, which are 100 ft long and 8 ft high, and the extension of 13 existing bridges to provide 40 ft of land along the drainage canals under the bridges. The spacing of the crossings is roughly 1 mi apart. Fencing to cause animals to use the crossings will be 10 ft high with outriggers and three strands of barbed wire, except at crossings, where fencing will be 12 ft high with outriggers and barbed wire. Although the crossings and fencing are not completely finished, panthers and other animals are currently passing through these structures, indicating that the constructed crossings are being used.