Tip For Discount Travel Transportation
If you're looking for the cheapest way to get from one city to another, you might want to check out the "Chinatown Bus" services. According to GotoBus.com, these services were started "in the late 1990s when an entrepreneur in New York's Chinatown started running daily bus service from Chinatown in New York to Chinatown in Boston." They offer basically the same service as traditional bus companies, but at much lower prices. The low prices soon attracted students, budget travelers and others beyond the Chinese residents it was initially intended for.
The success of the low budget bus service encouraged other bus companies to copy the model and they began to offer similar services in other cities. Now you can find this type of bus service in many major cities across the US. With the expansion of these bus services, the term "Chinatown bus" has since morphed from the literal meaning to encompass any low-cost/low-frills bus service. These bus operators are also sometimes referred to as "curbside" operators.
You can expect the following from these types of service:
No frills service--the driver may be the ticket collector; there will not be a lot of customer service. Comfortable buses. Despite the low fares buses are usually quite nice. Most buses are comparable to Greyhound and many are actually more deluxe. Communication challenges. Drivers are legally required to speak enough English to help passengers in the case of emergency. In reality this is often adhered to rather loosely. At the very least, expect your driver to have an accent. Possible delays. Many of these bus routes are on highly congested roads. When the roads are busy, expect delays. Rest stops. Buses will have a lavatory on board but there is usually a 10 or 15 minute bathroom break on trips over 4 hours. Don't be late returning to the bus, the driver will not count heads before leaving at the appointed time. Full buses. Buses definitely sell out at peak times (weekends and evenings). Book ahead or get there early if you want to secure a seat. Plastic Bags. An odd little quirk on Chinatown buses is that every aisle seat usually has a plastic grocery bag tied to the arm. I guess they find this is the best way to keep the buses clean.
If you're looking for a cheap alternative to travel between major cities and don't mind a no-frills aspect when travelling, "Chinatown Buses" may be a perfect way to keep your travel budget low.

Comments
I've taken the Chinatown buses several times. Very economical. Sometimes Greyhound will run specials that compete directly with the Chinatown buses. This might be worthwhile depending on how much luggage you have and where you live. The Chinatown bus pickup in NY is very far from the subway whereas Greyhound is much closer. You may have to transfer to get off at the Chinatown subway stop, but the Greyhound station is at Times Square.
Also I wouldn't be suprised if the driver makes stops to pick up random people on the street and then drops them off at their home, before they drop you off.
See also www.megabus.com/. (I'm not affiliated with them, but I've used them.)
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