https://www.cdc.gov/coronavirus/2019-ncov/cases-in-us.html
This CDC page presents the spread of the coronavirus in several ways.
There are several charts showing the numbers.
There is an interactive map of the US showing the cases in each state, with detail from hovering over the state in question. This gives a good visualization of where the most cases are.
There is also an interactive map of which states are currently testing for the virus and which are not.