Thanks for your question. This is definitely an important thing to be clear on. As it appears you already know, heavy rainfall events in the NE have increased by 71%, as shown in the map on the climate section of our website, and all areas of the U.S. are increasing in heavy rainfall events (with the exception of Hawaii).
In terms of the actual amount of precipitation, average precipitation over the entire U.S. has increased by roughly 5% since 1900, and we can look at the regional and seasonal signals that relate to this.
On a regional level, precipitation has increased the most in the Northeast (8%), Midwest (9%), and southern Great Plains (8%) since 1991. Areas in the Southeast and Southwest have had mixed areas of increases and increases.
In terms of future precipitation projections, given how climate change is predicted to impact atmospheric circulation and capacity, the Northern U.S. is generally projected to experience more precipitation in the winter and spring, with the Southwest projected to experience less precipitation, particularly in the Spring. Overall as well, the contrast between wet and dry areas is projected to continue to increase in the U.S. and globally.
(This information comes from the National Climate Assessment, available at globalchange.gov)
I hope this answers your question, and feel free to continue a dialogue with us or others on the forum if needed.