Copyright in the United States is conferred upon publication. Copyright protection subsists from the time the work is created in fixed form. The copyright in the work of authorship immediately becomes the property of the author who created the work.
Every website is on a computer somewhere as zeros and ones.
Physically speaking, most websites will fit on a floppy disk. This is tangible property. The files you upload, the images you spend hours getting just right, the text you display is a tangible medium of expression. It can be viewed, printed, and copied. Recent Internet Copyright and Trademark infringement lawsuits also support the concept of a website and images as tangible mediums of expression.