There are two common ways to get here: Fly into Mexico City and take the bus that goes directly from the airport to Querétaro, or fly into the León/Guanajuato airport. Zacatecas, San Luis Potosí, and Querétaro also have international airports that receive a few flights from the U.S. Or you can drive or take a bus from the U.S. border. From Texas, the first of the silver cities you will reach is San Luis Potosí (which, by the way, bills itself to the rest of Mexico as the "Gateway to the United States").
Once in the region, you'll find the roads are good, but not great, and the smaller ones are poorly marked. Driving within these towns can be maddening due to convoluted, narrow streets and bizarre traffic routing (especially in Guanajuato and Zacatecas). If you ever have difficulty navigating into the center of town, simply hail a cab to lead the way. Parking can also be a problem; I have included, when possible, good motels where you can park and leave your car for the length of your visit. If you prefer to travel by bus, you'll find frequent, inexpensive first-class buses connecting all these cities, which are only a few hours apart from each other.
The region has a short rainy season from June through September, which is a good time to come. I also like late fall, winter, and early spring. The hottest month is May (and sometimes early June before the rains arrive). May can also be smoky because it's when many farmers burn the stubble in their cornfields before the spring planting. Wherever you elect to visit, I recommend a stay of at least 3 days per destination -- a good part of their charm goes unappreciated if you press too much to see everything.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.