Beyonce covered the $100,000 (about R1.8m) cost of keeping local trains running after weather delayed her concert by two hours.
The 'Formation' singer took her 'Renaissance World Tour' to FedEx Field in North Englewood, Maryland, on Sunday but fans who had arrived early for the show were greeted with a shelter-in-place warning at around 6.30pm, meaning the 41-year-old megastar was unable to take to the stage until the storm cleared.
An announcement shared to the venue's official Twitter account read: "Due to lightning in the area, we are currently under a shelter in place order.
"Fans outside of gates and in the parking lots are asked to return to their cars. All fans inside of the stadium are asked to shelter in place under covered concourse areas and ramps until further notice. Thank you for your patience."
But at around 8.25pm, the 50 000 concertgoers were given the "all clear" and told to return to their seats, and it was announced Metro service hours would be extended to help those who had used public transport to get to the delayed show get home safely.
According to ABC7, Beyonce and the tour took on the $100,000 cost of running more trains, keeping all 98 stations open for fans to exit, as well as other operational expenses.
However, users were only able to enter the network at Morgan Boulevard, the closest station to the venue, with all others exit only.
Meanwhile, during the concert, fans noted Beyonce name-checked Lizzo again during her performance of 'Break My Soul (The Queens Remix)'.
A few days before, the former Destiny's Child star swapped the line 'Badu, Lizzo, Kelly Row' and just repeated 'Badu' four times, which many saw as a deliberate snub to the 'Good As Hell' hitmaker after she was sued by three of her former backing dancers.