Final answer:
Lidocaine is the most widely used anesthetic in the U.S. due to its effectiveness as a sodium channel blocker, causing reversible local loss of sensation.
Step-by-step explanation:
The most popular anesthetic used in the U.S. today is lidocaine. It is a local anesthetic that acts as a sodium channel blocker to prevent sodium ions from moving across the neuronal membrane, contributing to its effectiveness. This action results in a reversible loss of sensation in a specific area without affecting consciousness. Lidocaine is widely used in dental procedures, minor surgeries, and is also utilized in some instances as a topical agent for numbing the skin. While other anesthetics like novocaine (procaine) and cocaine have historical significance, lidocaine is preferred in contemporary medical practice for its efficacy and relatively mild side-effect profile.