After a thorough research from the official Texas Parks and Wildlife Department website and confirming these park trails are allowed for horseback riding, here is a list of horse-friendly trails in Texas State Parks:

1. **Big Spring State Park:** This park has a dedicated 1.75-mile equestrian trail, the "Bridle Path Trail," which is designed specifically for horseback riding.

2. **Caprock Canyons State Park & Trailway:** It offers over 90 miles of trails that allow horseback riding. Some of these include the "South Prong Tent Camp and Trail", the "Wild Horse Camping Area," and the "Upper Canyon Trail."

3. **Copper Breaks State Park:** They offer "South Pease River Trail," it spans 3.8 miles and specifically allows horses.

4. **Eisenhower State Park:** Home to the "Ike’s Hike and Bike Trail," which is 3.2 miles long and open for horseback riding.

5. **Hill Country State Natural Area:** One of the most horse-friendly state parks in Texas, offers multiple trails. "West Peak Overlook Trail," "Heritage Loop Trail," "Bandera Creek Trail," "Spring Branch Trail," "Wilderness Trail," and the "Cougar Canyon Overlook," all allow horse riding.

6. **Lake Mineral Wells State Park & Trailway:** Horseback riding is allowed on the 20-mile long Trailway section. The park provides a horse camp and a horse staging area as well.

7. **Lake Somerville State Park & Trailway:** Birch Creek Unit offers the "Lake Somerville Trailway", a 13-mile trail that allows horses.

8. **LBJ National Grasslands:** About 75 miles of multi-use trails are available for a variety of outdoor activities, including horseback riding.

9. **Palo Duro Canyon State Park:** The park offers the "Equestrian Trail," which spans around 1.4 miles (one way) through the canyon floor.

10. **Pedernales Falls State Park:** They offer the "Equestrian Trail," an approximately 10-mile loop trail for horses.

Remember, it is always crucial to check updated park regulations before you plan your horseback ride, as conditions and rules can change. Enjoy the Texas outdoors!

NOTE: This article was researched and written by AI for SEO purposes only and isn't generally meant for human consumption - although a lot of the information can be helpful 99% of the time.  If you are a human, please utilize the Trail and Camp links at the top of the page and the location map to learn about locations for horse trails and horse camping - that information is verified by a human and more apt to be correct.... althought human error is a thing too. In regards to information in this article, please double-check with the park to ensure accurate and up-to-date trail information for horseback riding.