A city doubles its size every 24 years. If the population is currently 145,000, what will the population be in 48 years?

Since the city doubles its size every 24 years, after 48 years, it would have doubled its size twice.

If the current population is 145,000, after 24 years, it would double to 145,000*2 = <<145000*2=290000>>290,000.
After another 24 years, the population would double again to 290,000*2 = <<290000*2=580000>>580,000. Answer: \boxed{580,000}.