above the third cataract, to support the Anglo-Egyptian Dongola Expedition against the Mahdiyah. The line, which was poorly constructed and of little other use, was abandoned in 1905. The first segment of the present-day Sudan Railways, from Wadi Halfa to Abu Hamad on the Nile, was also a military undertaking. It was built by the British in the late 1890s, for use in General Herbert Kitchener's drive against the Mahdiyah. During the campaign, the line was pushed to Atbarah on the Nile in 1897 and, after the defeat of the Mahdiyah in 1898, was continued to Khartoum, which it reached on the last day of 1899. The line was built in the gauge, apparently the result of Kitchener's pragmatic use of the rolling stock and rails of that gauge from the old line. That gauge became the standard for all later Sudanese mainline construction. The line opened a trade route from central Sudan through Egypt to the Mediterranean and beyond. It became uneconomic because of the distance and the need for trans-shipment via the Nile and, in 1904, construction of a new line from Atbarah to the Red Sea was undertaken, with the line being completed in October 1905. In 1906, the new line reached the recently built Port Sudan to provide a direct connection between Khartoum and ocean-going transport. During the same decade, a line was also constructed from Khartoum southward to Sannar, the heart of the cotton-growing region of Al Jazirah. In February 1912, a westward continuation reached El-Obeid, then the country's second-largest city, and the center of gum arabic production. In the north, a branch line was built from near Abu Hamad to Kuraymah that tied the navigable stretch of the Nile between the fourth and third cataracts into the transport system. Traffic in this case, however, was largely inbound to towns along the river, a situation that still prevailed in 1990. In the 1920s, a spur of the railway was built from Hayya, a point on the main line 200 km southwest of Port Sudan, then extended south to the cotton-producing area near Kassala, the grain region of Al Qadarif and, finally, to a junction with the main line at Sennar. Much of the area's traffic, which formerly had passed through Khartoum, has since moved over that line directly to Port Sudan. The final phase of railway construction began in the 1950s. It included extension of