After having done quite a bit of research I have been unable to find a single shapefile download which includes all of the current 3,141 counties with their associating data clipped with the highest resolution shoreline data available.
Does anyone know where I can find this data?
I am not sure how you are going to know or check the shoreline clipped aspect of your question.
Esri has some datasets that are described as detailed (dtl).
However you would need to aquire the Data Distribution Application (DDA) [see page 8 of the pdf] to get them into shapefile as they originate as *.sdc format.
Data is provided in Esri’s compressed, direct-read, high-performance Smart Data Compression (SDC) format
dtl_wat, dtl_riv, dtl_cnty_ln, etc.
As you don't describe the use I would perhaps suggest using the esri services available online.
The esri data-and-maps is also described here and in pdf along with redistribution rights.
The download search begins here.
Also just found the high resolution shoreline data, and a great blog on how it can be used.
You're best bet may be to look for each state individually, or at least regionally.
The RAMONA GIS inventory, a NSGIC project, lists data layers and associated metadata for all 50 states. Information is voluntarily provided, so some states have more info. than others. Data cannot be downloaded from RAMONA, but the brief and detailed metadata will include download address, ordering info, and/or contact info.
Furthermore, The NSGIC website has a list of GIS contacts for all 50 states. The contacts tend to be managers/leaders, so they may be able to point you to appropriate resources for their state.
This approach will most likely lead to datasets in several different resolutions/scales. However, I think it is your best approach if you're looking for larger scale data.