But by the 1950s, clocks with improved batteries and oscillating quartz crystal resonators began to replace consumer electric clocks that synchronized with the

But by the 1950s, clocks with improved batteries and oscillating quartz crystal resonators began to replace consumer electric clocks that synchronized with the power grid. That sounds a little early; mains-referenced clocks continue to be widespread into the 21st century, especially in bedside clock radios. In my experience, the ones based on quartz oscillators drift even more than mains-referenced ones over the long term.