In the United States, cloverleaf interchanges existed long before the Interstate system. They were originally created for busier interchanges that the original diamond interchange system could not handle. Their chief advantage was that they were free-flowing and did not require the use of such devices as traffic signals. This not only made them a viable option for interchanges between freeways (where such devices are typically not an option), but they could also be used for very busy arterials where signals could present congestion problems.