They are certainly not the common blankets that you and I are aware of. In fact, very few may have even heard the term. But thankfully, authentic san marcos blankets are not hard to find. The era of e-commerce and online shopping makes it easy for common laymen shoppers ( like me of course !) to get these Mexican beauties from far off areas.
The first thing that you will notice is the vibrancy of colors. I had personally not seen so much flair in this category. My mother used to buy Korean mink blankets from local markets but that is a different breed altogether. She was surprised to discover the beauty of these vintage collections.
A simple online research made me realize that the artwork is a great bonding factors among Latinos. They have a long and rich history behind the making of beautiful patterns and figures that you normally find woven on them. Color combinations seem to pop out from the surface because there is a unique richness in blending process. The same effect is seen in full figure designs.
The Mexican varieties were traditionally sold by street hawkers. Sometimes the artist would themselves set up their own shops and interact with customers. The authentic varieties have had a lot of makeover in the past few decades but the unique flair, thankfully, still remains.
If you are the proud owner of any form of San Marcos blanket, take some time out to explain the craftwork to someone in your circle. This would genuinely help in making this craft form continue in its original form.