Saudi women hit the road as legal drivers for the first time Sunday, with a mix of celebration as one gender barrier fell and some activists called for the repeal of others.

Minutes after midnight in Saudi Arabia, a leader in the right-to-drive movement, Manal al-Sharif, launched the Twitter campaign #Miles4Freedom to seek an end to the kingdom’s guardianship system, which requires a woman to get approval from a male relative for decisions such as travel abroad.

The end of male-only driving is seen as part of gradual cultural changes led by Crown Prince Mohammed bin Salman, the next in line to the throne.

But allowing women to drive — like many changes in the ultraconservative kingdom — has been met with opposition from some conservatives and underscores deeper internal tensions over the crown prince’s challenges to the old order.

Some women immediately got behind the wheel in their first legal road trips as drivers in the kingdom.

“I thought I would never witness this day,” said one of the many social media posts hours after the law took effect. “I’m incredibly happy Congratulations girls we did it.”

As the first female drivers took to the road in the eastern city of Khobar, onlookers cheered as police looked on. “We are ready, and it will totally change our life,” Samira al-Ghamdi, a 47-year-old psychologist from Jiddah, told Al Jazeera. She was one of the first women issued a license under the new law.

A handful of men took part in the festivities, as well.

Amanda Erickson contributed to this report.