the west side branch of the first subway was extended northward to a temporary terminus of 221st street and broadway on march 12, 1906 with the first open station at dyckman street, as the stations at 168th street, 181st street, and 191st street were not yet completed. this extension was served by shuttle trains operating between 157th street and 221st street until may 30, 1906 when express trains began running through to 221st street.