Who is the highest selling girl group of all time?
No context provided
Who is the highest selling girl group of all time worldwide?
Spice Girls
No context provided
Who is the highest selling girl group of all time in the  United States?
TLC
List of best-selling girl groups
https://en.wikipedia.org/wiki/List%20of%20best-selling%20girl%20groups
Sales figures records in most countries are not available before the 1990s, so it is difficult to accurately determine best-selling records, either by country or worldwide. Certification levels have been used for most countries, but certification was not common until the 1970s in the US and UK, and later in other countries. In addition, in many countries certification is for shipments of a record to retailers, rather than actual sales. Complicating matters further are the changes from 2010 onwards as certifications have become based on a combined figure of sales and streaming, instead of sales alone.
List of best-selling girl groups
The Spice Girls have sold 100 million records worldwide
Spice Girls
TLC is the best-selling female singing group in American music history, with 23 million certified albums.
TLC (group)
In most countries, the sales figures records of girl groups are not available before the 1990s, so it is difficult to accurately determine best-selling artists, either by country or worldwide. Complicating matters further, in many countries, certification is for shipments of a record to retailers, rather than actual sales, and from 2010 onwards, certifications have become based on a combined figure of sales and streaming, instead of sales alone. Nonetheless, with the information available, the highest selling girl group of all time worldwide is the Spice Girls, having sold 100 million records. Alternatively, in the US, the title goes to TLC, with 23 million certified albums.