What would the reduction in CO2 emissions be if the US switched completely to natural gas from coal?

If the US was able to shut down all of it’s coal fired power plants and replace them with natural gas, what would the reduction in CO2 be? I’ve seen figures of 50% tossed about, but I’m unsure what it would be and I’m curious. Please keep the answers to this narrow focus…just want to know what the reduction in emissions would be if we were just able to replace all our coal plants with natural gas plants of the same production capacity. You could include any additional transport costs if that adds to CO2 on the front or back end. What I’m looking for is the net gain or loss, assuming there is one.

Based on this

Here is a rough estimate;

Electricity accounted for 28 percent of the 6511 million tons of carbon equivalent in the U.S., so about 1823 million tons.

Coal accounted for 2/3’s of that total, so about 1200 million tons, natural gas accounts for 600 million. Natural gas is about twice as efficient as coal in terms of CO2 per unit of energy produced, so switching to coal to gas would save about 600 million tons, or 10 percent of the total.

Ok, thanks…that gives me a ballpark to understand the numbers and give it some context.