There's very little difference in US taxes between one-way ticket from US-CA and CA-US. A $240 USD ticket will have about $30 in taxes for US-CA and about $35 for CA-US (in USD). For higher priced tickets, the difference gets less and less as US-CA one-way tickets are subject to 7.5% US domestic excise tax while CA-US one-way are not. While state and local governments may back improvement bonds, in the vast majority of cases they are paid of via PFC's, gate leases, landing fees and other airport charges. The FAA does fund many improvements (particularly for smaller airports with limited funding). But this is largely funded by US 7.5% domestic excise tax and US $4.20 domestic segment tax.