It typically takes from 2 to 5 weeks to process an ordinary US visa application. That is assuming the application is straightforward and there are no reasons to deny it.
Usually, a Non-Immigrant Visa will be completed more quickly than an Immigrant Visa. US Immigrant visas could take from 6 to 12 months to process.
Certain employer based visas are eligible for Premium Processing Service. The employer can pay an additional fee of US$1410.00 to have the visa processed more quickly. In this case, an employer-sponsored visa could be approved within just 2 weeks.