Being US citizens, we often take for granted our seamless travel protocols, making sure only passports and credit cards are in order before we leave for an international trip. Here's a list of popular countries that require US citizens to acquire a visa in advance. Please note that the links below are for travel for holiday/tourism, business travelers should investigate further.
A quick online process for an ETA and a $20 fee for Americans. Apply online here. You must be outside the country when you apply.
US citizens can apply for a single or multiple entry L visa here.
US citizens can get a one year multiple entry tourist visa by applying to the Travisa outsourcing centers in their geographical area.
A sponsorship letter, a fee of $124 and 4-6 weeks processing time is required for the Pakistan visa.
An official invitation and multiple forms for multiple entry visas is required for a Russian visa.
You will need an itinerary and a sponsor and can apply online here.
One or three month visas are issued within six days at the Travisa outsourcing center.
The host/sponsor must get approval for your visit at the Ministry of Foreign Affairs prior to your application being submitted. Apply here.
Visas can be issued for 90 days or 10 years. A yellow fever vaccination certificate is required with your application.