How were individual times taken in mass running events prior to transponders?

Factual Questions
1

After I ran in our town’s annual 7.5 km race yesterday as one of 1,373 people to finish I got to wonder: how was it economically practicable to take individual times in such mass events before transponder systems were available?

The system used was with a transponder to be bound into one’s shoelaces, and antenna mats at the start and finish lines. The time at passing the start and finish antennas was clocked and a net running time was calculated (fortunately, as it took me 66 seconds from the starting signal to reach the start line…). The resulting dataset can, of course, be processed with pretty standard software.

Only: How was this done before transponders were available? It is obviously economically unfeasible, with a race of say 2,000 amateur runners to have 2,000 people stand by with stopwatches. Also the arrivals in the main part of the field would be much too close together to be timed by someone frantically typing numbers into a keyboard (not to mention that this would be much too error prone).

So, how was it done in mass-participation, low-participation-cost races before transponders?

2

My understanding is that the runners who were truly competeing to win the event (maybe the top 50?) were put on the front line and considered to have started at the same time. Then it just becomes the first to cross the line. For the others, their order of finish would be easy to determine at the finish line and their overall time was less important. If you were really interested in your exact time, you kept it yourself on a wristwatch.