According to HTC Peter Chou, HTC growth in the U.S. market has been "faster than others" which is probably due in large part to Android's success here. HTC was the first phone manufacturer to release an Android device and has been on a roll ever since, improving their hardware, writing new software, and basically building better phones. Our apologies to other phone manufacturers but HTC has shown the world how awesome Android can be.
Because of its recent success, HTC's relationship with U.S. carriers have also improved. Chou specifically mentions the Nexus One (which will be available on all 4 carriers) and the Evo 4G (which is on Sprint) as devices that have brought firmer support from US carriers. Chou also says:
"[Verizon and T-Mobile] started treating us as their first-tier suppliers last year. It was difficult for us [to boost our sales] without their support. But their endorsements became a strong momentum" for growth"