You can sort of get away with targeting 2-3 cities with a single page, but it's less than ideal. If you cover a lot of areas, consider breaking your site down into silos. /city1, /city2, /city3, then into the services for each /city1/service1, /city1/service2, /city1/service3, or even further into something like /city1/service2/something-related-to-service2, etc. The content needs to be unique on each page of course, but this will let you target multiple cities easier. How far your break them down and how much content you make for each can be determined by the volume of searches or importance of the city to you. Some cities you might want to just build a city page that lists all services (such as low importance, low search volume, or low competition areas,) others you may want just a few main service pages for, and other important locations you may want pages for all the services you offer.