Business leaders estimate that Britain's economy lost up to £20 million every day the line in Devon - wrecked on February 4 following winter storms - was shut.
Yesterday's 5.34am train from Exeter to Paignton became the first to travel along the vital track, which links Devon and Cornwall to the rest of the country.
The railway line was repaired by a 300-strong Network Rail team, nicknamed the "orange army", who worked round-the-clock for 56 days to complete repairs before schedule.
Their efforts were praised as Herculean by David Cameron, who urged people to visit the south west after arriving at the station.
Mr Cameron, who pledged to return to the region for his own holiday in the summer, called for three cheers for the "orange army" during a speech at the station.
The £35m repair work was completed in time for tourists to travel into the south west by rail for the Easter holidays, providing relief for local business owners and residents. Gordon Oliver, the mayor of Torbay, said further investment was needed for transport in the region but said the reopening was a "big step in the right direction".