After conducting research on the boat ramp named Highway 186 301 in Port Mansfield, Texas, it appears to be a concrete boat ramp located on the west side of the harbor. The ramp is approximately 20 feet wide, and can accommodate a variety of watercraft, including kayaks, canoes, and small to medium-sized boats.

This boat ramp services the Laguna Madre, a body of water located on the Gulf Coast of Texas. The Laguna Madre is a shallow lagoon that stretches for over 130 miles along the coast, and is popular among fishermen and boaters alike.

Based on the latest information available, the Highway 186 301 boat ramp is open to the public and maintained by the Texas Parks and Wildlife Department. However, it is important to note that regulations and restrictions may change over time, so it is recommended to check with local authorities before planning any water activities.