In general, a common-grade 1917 act or 1863 one dollar silver certificate in circulated condition is worth between $2 and $5. However, certain rare and high-grade examples can be worth significantly more. For example, a 1917 act one dollar silver certificate in uncirculated condition with a "star" designation can be worth hundreds or even thousands of dollars.
If you have a 1917 act or 1863 one dollar bill and are interested in determining its value, it's a good idea to consult a professional numismatist or coin dealer who specializes in paper money. They can evaluate the condition and rarity of your bill and provide you with an accurate estimate of its value.