In a large container, combine cucumbers, onions and salt. Cover with crushed ice and mix well. Let stand for 3 hours. Drain; rinse and drain again.
In a Dutch oven, combine sugar, vinegar and seasonings; bring to a boil. Add cucumber mixture; return to a boil. Remove from the heat.
Carefully ladle hot mixture into 7 hot pint jars, leaving ½-in. headspace. Remove air bubbles and adjust headspace, if necessary, by adding hot mixture. Wipe rims. Center lids on jars; screw on bands until fingertip tight. Place jars in canner with simmering water, ensuring that jars are completely covered with water. Bring to a boil; process for 15 minutes. Remove jars and cool.
