Here is the Chinese Consulate link for visa applications:
http://www.china-embassy.org/eng/visas/hrsq/
If you don't want to or can't get to the consulate, visa processing services will do it for a fee. We used Visa Central on advice from our tour provider.
Visa Express is a non-government based service authorized by the
Chinese consulate to expedite Chinese visas. We offer reasonable and
competitive price, our regular visa service rate start from $79 on top
of the consulate fee. However, you can go to the Chinese consulate to
apply the visa in person to avoid paying additional fees. Our
additional service fees include visa specialists to help you with your
application forms to avoid delays and the hassle of having to wait in
line yourself. We are here to assist you in the easiest and quickest
ways possible, and we serve nationwide!
http://www.china-embassy.org/eng/visas/faq/#2
I am a U.S. citizen, can I apply for a Chinese visa at the port of entry?
U.S. citizens must obtain a visa before arrival in China. You are not eligible for a landing visa.
Submission and Collection Where should I apply for a visa? Must I
appear in person to submit my application? May I use a visa service?
You may apply for a visa at a Chinese Embassy or Consulate General
based on your State of residence. (Check Service Area Map). You need
to complete and sign the visa form and prepare necessary supporting
documents and have your friend or a visa service help submit your
application. You don't have to appear in person unless required by a
consular officer.
Do I need to schedule an appointment for visa application?
No. You may visit the Visa Office anytime during business hours unless
otherwise required by a consular officer.
Can I apply for a visa by mail? Could you mail the passport with visa
back to me?
No. We do NOT accept mail-in visa applications. We do NOT provide
mail-back service either.
What do I need to know if I go to Visa Office to submit my
application?
Please make sure you have checked our website and prepared all
necessary documents BEFORE you come to the Visa Office. Oversize
baggage or hazardous objects are NOT allowed in the Visa Office. You
must pass a security check at the entrance of the Visa Office. Once in
the office, please take a number for visa application and wait for
your turn. Proceed to the window that shows your number and submit
your application. You will be given a pick-up slip for your
application and passport accepted. Please retain the slip and return
to the Visa Office on or after the date shown on the slip to pick up
your passport. You will need to pay for your visa on the pick-up day.
If no pick-up date is shown on the slip, you need to wait for a call
or mail notification from the Visa Office as your application may
require longer processing time. You may also contact us for inquiries.