I'm a US passport holder, staying in Shenzhen for 2 days. Can I get 5day VOA, flying directly fromUS

Part one:

It's never safe to rely on obtaining a Shenzhen VOA on arrival. Visas are by definition something that can be granted, but also denied for no reason. Exactly for this reason, many airline companies are reluctant to take those passengers to Shenzhen that state that they will be flying and obtain VOA upon arrival. In reality, it is airlines that make the greatest obstacle for such an option. As always, I suggest you to rely on two options, one is Shenzhen VOA on arrival (upon landing), but if you are denied boarding, you will declare that you will travel to Hong Kong via Shenzhen using 144 hour visa free transit.

To be allowed to have this back up option, you will have to book a ferry ticket from Shenzhen Shekou port to Hong Kong through CKS - Chu Kong Passenger Transport company website. Please, keep in mind that this ferry has to have its departure at least 24 hours and 1 minute distant from your scheduled arrival by plane to Shenzhen. You will print out an e-confirmation that you will receive on your email and you will use this e-confirmation as a proof that you will be traveling to Hong Kong. If you are forced to use this option, you will really take this ferry to Hong Kong and after your arrival in Hong Kong, you can depart immediately back to Shenzhen, preferably by overland route. On the border crossing you will then apply for a Shenzhen visa and proceed to Shenzhen with this short Hong Kong interruption. After your stay in Shenzhen you are allowed to depart from Shenzhen airport directly to US.

Part two:

To conclude... You will at first declare that you will travel to Shenzhen where you will apply for a Shenzhen VOA. If allowed, you will travel to Shenzhen, obtain a VOA and enjoy your stay in the city and you will also make a refund of your paid ferry ticket online. You will get back a lion's share of the amount you have paid minus some handling and administrative fees. In case if you are not allowed to travel using this option, you will promptly declare that you will travel to Hong Kong using 144 hour visa free transit. You will definitely reach Shenzhen using these two schemes, but you should definitely try Shenzhen VOA as the first option. Also, you should have in mind that this, 144 hour TWOV option is essential and will make your travel completely eligible in every sense.