From the Q2 earnings letter:
"Expanding Model S Demand
At Tesla, we see a clear distinction between demand and deliveries. We measure demand by the number of cars that have been ordered. An order occurs when a customer selects their vehicle configuration and pays the nonrefundable cash deposit. Deliveries, on the other hand, are the fulfillment of those orders. The number of deliveries in a quarter is influenced by three main factors: our ability to increase production; the allocation of that production among our North American, European and Asian markets; and the need to fill the in-transit pipeline for future deliveries in each region. This quarter, for example, we delivered 7,579 Model S vehicles, slightly ahead of guidance and up by more than 17% sequentially. However, even though we increased both production and deliveries, average global delivery wait times increased because our production growth was unable to keep pace with increased demand.
Model S orders, and thus demand, continue to grow even in our most established markets. In both North America and Europe, Q2 Model S orders increased sequentially at a much faster rate than for the rest of the automotive industry. Accordingly, we believe these markets remain under-penetrated. We expect demand to continue to increase worldwide as we continue to grow our customer support infrastructure and broaden the appeal of our products, and as consumer awareness improves."
This should put to rest the issue that US demand is not declining, but increasing.