Building a frontier town uses rules borrowed from Pathfinder for town building, downtime building, etc.

http://www.d20pfsrd.com/gamemastering/other-rules/downtime/ Downtime rules control various actions you can do with a day of downtime between adventures, including managing and building individual businesses.

http://www.d20pfsrd.com/gamemastering/other-rules/kingdom-building/ While towns as 'kingdoms' are really vassal territories to the country that founded the colony (at least as far as the country in question is concerned), these rules allow you to build towns, and may be convertible to handle things on a town by town basis instead of a kingdom by kingdom basis.

Building a settlement uses a modified version of the rules for kingdom building. Towns are handled as little miniature kingdoms, with roles that citizens may play in making the town become bigger and better over time.

Mayor: The person responsible for keeping the town in order. “The Ruler”.

Guard Captain: The person responsible for managing the defense of the town in times of crisis. “The General”.

Ambassador: The person responsible for managing diplomatic and trade agreements with other towns and cultures. “The Diplomat”.

High Priest: The person responsible for managing the religious development of the community. “The High Priest”.

High Wizard: The person responsible for managing the magical development of the community. “The Magister”.

Sheriff: The person responsible for maintaining law and order in the community. “The Royal Enforcer”.

Treasurer: The person responsible for collecting taxes for the town, managing payment for public projects, and paying taxes to the country. “The Treasurer”.

You will note that some kingdom roles are not accounted for; they are not necessary on this scale, and in truth, many of these positions are not entirely necessary depending on a town's size. However, they are no less demanding than a kingdom job; in order to qualify as filled, the person in a particular role must spend at least seven downtime days on performing the tasks related to that role. Running a business also uses downtime days; so a mayor who owns the local general store must divide his attention to some extent, and probably hires a manager and staff to take care of the day to day details…

Build Points are used on the colony scale to improve a town. One build point is roughly equivalent to 4,000 gold pieces in supplies and labor.

For managing downtime, and developing individual buildings as opposed to a block of flats supported by the crown, we have Capital. Capital comes in four forms - Goods, Influence, Labor, and Magic - and may be bought or earned.