You don't need a partner as in tennis or racquetball, or enough participants to make two teams as in basketball or baseball. Running works well as a solitary sport. Still, there are times when it's fun to run with others. One way to find other runners is to join a running club. Many clubs organize training runs or provide classes.
Many major newspapers have running columns, or list events and activities.
Look for names and phone numbers in newspapers and local specialty sports publications. Call for information. Many road races are sponsored by running clubs. Look for runners with singlets featuring the name of their clubs. They want to locate you even more than you want to locate them.