Line A is the oldest line of the Buenos Aires Underground. Opened to the public on 1 December 1913, it was the first underground line in South America, the Southern Hemisphere and the Spanish-speaking world. It made Buenos Aires the 13th city in the world to have an underground transport service. The line stretches 9.8 km from Plaza de Mayo and San Pedrito and runs under the full length of the Avenida de Mayo and part of the Avenida Rivadavia, and is used by 258,000 people per day. On the first day of public service (18 December 1913), it carried 220,000 passengers. Line A used the cars used at its inauguration for just under a century. These cars were built by Belgian company La Brugeoise starting in 1913 and were refurbished in 1927 when their wooden structure was modified for underground-only use. A peculiarity of the original "pantograph" cars on the "underground tramway" was that until 1926 they had both low doors at the ends for boarding from the street and high doors in the middle for loading from platforms in the tunnel. For this reason, Line A might also be considered the continent's first "light rail subway". The old wooden cars were removed in 2013, and replaced by modern cars. The line has been extended twice since the completion of the original line in 1914, with the most recent two-station extension of San José de Flores and San Pedrito entering service on 27 September 2013. History During the first decade of the 20th century in Buenos Aires, road traffic had sharply increased due to a growing population. In 1903 the city had 895,381 inhabitants and there were 4,791 horse-drawn carriages and 60 cars, while by 1913 there were 1,457,885 people, with 6,211 carriages and 7,438 automobiles. Because it was necessary to create new forms of mass transit, in 1909 the Congress awarded Ferrocarril del Oeste (FCO) (Buenos Aires Western Railway) a concession to build a two-way underground railway that would join the main route of the Buenos Aires Western Railway (currently the Sarmiento Railway) at Once railway station, near Sadi Carnot Street (now Mario Bravo) with the port. However, on 28 December 1909 the Municipality of the City of Buenos Aires gave a concession to the Anglo-Argentine Tramways Company (AATC), which operated 80% of Buenos Aires' tram system at the time (making it perhaps the largest in the world)