As commuters crammed onto buses and searched for alternate modes of transport, traffic on the main avenues of Buenos Aires stalled. Some hopped on bikes or trekked to work on foot.
Talks to end the strike – the longest since 1994 – fell apart late Tuesday after the metro workers union insisted on a 28 percent pay increase.
“We demand the start of salary negotiations,” said union official Andres Fonte. “We’ve been waiting for five days.”
The protest comes amid a prolonged political struggle between the government of President Cristina Kirchner and Buenos Aires Mayor Mauricio Macri.
Argentina’s federal government said in January it was turning over the management of the metro to the city.
But Macri, an opposition leader and aspiring presidential challenger in 2015, is refusing to take it on, saying federal authorities must first turn over the funds necessary to improve the system.
Argentina’s capital has a population of three million, but on weekdays the number soars with another three million flowing in from the surrounding area.
The metro, which spans 56.7 kilometers, links the city with its densely populated suburbs — and typically attracts about a million riders a day.
Normally, some 1.3 million vehicles pack the streets of Buenos Aires, including 36,000 taxi cabs and 9,800 buses, according to official figures. A decade ago, the total was 750,000.