What was the consensus estimate for the distance to the Perseus Arm before modern radio astronomy revised it?

Answer

Around 13,000 light-years

For many years, the consensus estimate for the separation between Earth and the Perseus Arm hovered near 13,000 light-years, with some earlier calculations suggesting 14,000 light-years.

What was the consensus estimate for the distance to the Perseus Arm before modern radio astronomy revised it?
galaxyastronomyDistanceEarthMilky WayPerseus Arm